linux/mm/zswap.c

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zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
/*
* zswap.c - zswap driver file
*
* zswap is a backend for frontswap that takes pages that are in the process
* of being swapped out and attempts to compress and store them in a
* RAM-based memory pool. This can result in a significant I/O reduction on
* the swap device and, in the case where decompressing from RAM is faster
* than reading from the swap device, can also improve workload performance.
*
* Copyright (C) 2012 Seth Jennings <sjenning@linux.vnet.ibm.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/cpu.h>
#include <linux/highmem.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/types.h>
#include <linux/atomic.h>
#include <linux/frontswap.h>
#include <linux/rbtree.h>
#include <linux/swap.h>
#include <linux/crypto.h>
#include <linux/mempool.h>
#include <linux/zpool.h>
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
#include <linux/mm_types.h>
#include <linux/page-flags.h>
#include <linux/swapops.h>
#include <linux/writeback.h>
#include <linux/pagemap.h>
/*********************************
* statistics
**********************************/
/* Total bytes used by the compressed storage */
static u64 zswap_pool_total_size;
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
/* The number of compressed pages currently stored in zswap */
static atomic_t zswap_stored_pages = ATOMIC_INIT(0);
zswap: same-filled pages handling Zswap is a cache which compresses the pages that are being swapped out and stores them into a dynamically allocated RAM-based memory pool. Experiments have shown that around 10-20% of pages stored in zswap are same-filled pages (i.e. contents of the page are all same), but these pages are handled as normal pages by compressing and allocating memory in the pool. This patch adds a check in zswap_frontswap_store() to identify same-filled page before compression of the page. If the page is a same-filled page, set zswap_entry.length to zero, save the same-filled value and skip the compression of the page and alloction of memory in zpool. In zswap_frontswap_load(), check if value of zswap_entry.length is zero corresponding to the page to be loaded. If zswap_entry.length is zero, fill the page with same-filled value. This saves the decompression time during load. On a ARM Quad Core 32-bit device with 1.5GB RAM by launching and relaunching different applications, out of ~64000 pages stored in zswap, ~11000 pages were same-value filled pages (including zero-filled pages) and ~9000 pages were zero-filled pages. An average of 17% of pages(including zero-filled pages) in zswap are same-value filled pages and 14% pages are zero-filled pages. An average of 3% of pages are same-filled non-zero pages. The below table shows the execution time profiling with the patch. Baseline With patch % Improvement ----------------------------------------------------------------- *Zswap Store Time 26.5ms 18ms 32% (of same value pages) *Zswap Load Time (of same value pages) 25.5ms 13ms 49% ----------------------------------------------------------------- On Ubuntu PC with 2GB RAM, while executing kernel build and other test scripts and running multimedia applications, out of 360000 pages stored in zswap 78000(~22%) of pages were found to be same-value filled pages (including zero-filled pages) and 64000(~17%) are zero-filled pages. So an average of %5 of pages are same-filled non-zero pages. The below table shows the execution time profiling with the patch. Baseline With patch % Improvement ----------------------------------------------------------------- *Zswap Store Time 91ms 74ms 19% (of same value pages) *Zswap Load Time 50ms 7.5ms 85% (of same value pages) ----------------------------------------------------------------- *The execution times may vary with test device used. Dan said: : I did test this patch out this week, and I added some instrumentation to : check the performance impact, and tested with a small program to try to : check the best and worst cases. : : When doing a lot of swap where all (or almost all) pages are same-value, I : found this patch does save both time and space, significantly. The exact : improvement in time and space depends on which compressor is being used, : but roughly agrees with the numbers you listed. : : In the worst case situation, where all (or almost all) pages have the : same-value *except* the final long (meaning, zswap will check each long on : the entire page but then still have to pass the page to the compressor), : the same-value check is around 10-15% of the total time spent in : zswap_frontswap_store(). That's a not-insignificant amount of time, but : it's not huge. Considering that most systems will probably be swapping : pages that aren't similar to the worst case (although I don't have any : data to know that), I'd say the improvement is worth the possible : worst-case performance impact. [srividya.dr@samsung.com: add memset_l instead of for loop] Link: http://lkml.kernel.org/r/20171018104832epcms5p1b2232e2236258de3d03d1344dde9fce0@epcms5p1 Signed-off-by: Srividya Desireddy <srividya.dr@samsung.com> Acked-by: Dan Streetman <ddstreet@ieee.org> Cc: Seth Jennings <sjenning@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Dinakar Reddy Pathireddy <dinakar.p@samsung.com> Cc: SHARAN ALLUR <sharan.allur@samsung.com> Cc: RAJIB BASU <rajib.basu@samsung.com> Cc: JUHUN KIM <juhunkim@samsung.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Timofey Titovets <nefelim4ag@gmail.com> Cc: Andi Kleen <ak@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 01:15:59 +01:00
/* The number of same-value filled pages currently stored in zswap */
static atomic_t zswap_same_filled_pages = ATOMIC_INIT(0);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
/*
* The statistics below are not protected from concurrent access for
* performance reasons so they may not be a 100% accurate. However,
* they do provide useful information on roughly how many times a
* certain event is occurring.
*/
/* Pool limit was hit (see zswap_max_pool_percent) */
static u64 zswap_pool_limit_hit;
/* Pages written back when pool limit was reached */
static u64 zswap_written_back_pages;
/* Store failed due to a reclaim failure after pool limit was reached */
static u64 zswap_reject_reclaim_fail;
/* Compressed page was too big for the allocator to (optimally) store */
static u64 zswap_reject_compress_poor;
/* Store failed because underlying allocator could not get memory */
static u64 zswap_reject_alloc_fail;
/* Store failed because the entry metadata could not be allocated (rare) */
static u64 zswap_reject_kmemcache_fail;
/* Duplicate store was encountered (rare) */
static u64 zswap_duplicate_entry;
/*********************************
* tunables
**********************************/
#define ZSWAP_PARAM_UNSET ""
/* Enable/disable zswap (disabled by default) */
static bool zswap_enabled;
zswap: disable changing params if init fails Add zswap_init_failed bool that prevents changing any of the module params, if init_zswap() fails, and set zswap_enabled to false. Change 'enabled' param to a callback, and check zswap_init_failed before allowing any change to 'enabled', 'zpool', or 'compressor' params. Any driver that is built-in to the kernel will not be unloaded if its init function returns error, and its module params remain accessible for users to change via sysfs. Since zswap uses param callbacks, which assume that zswap has been initialized, changing the zswap params after a failed initialization will result in WARNING due to the param callbacks expecting a pool to already exist. This prevents that by immediately exiting any of the param callbacks if initialization failed. This was reported here: https://marc.info/?l=linux-mm&m=147004228125528&w=4 And fixes this WARNING: [ 429.723476] WARNING: CPU: 0 PID: 5140 at mm/zswap.c:503 __zswap_pool_current+0x56/0x60 The warning is just noise, and not serious. However, when init fails, zswap frees all its percpu dstmem pages and its kmem cache. The kmem cache might be serious, if kmem_cache_alloc(NULL, gfp) has problems; but the percpu dstmem pages are definitely a problem, as they're used as temporary buffer for compressed pages before copying into place in the zpool. If the user does get zswap enabled after an init failure, then zswap will likely Oops on the first page it tries to compress (or worse, start corrupting memory). Fixes: 90b0fc26d5db ("zswap: change zpool/compressor at runtime") Link: http://lkml.kernel.org/r/20170124200259.16191-2-ddstreet@ieee.org Signed-off-by: Dan Streetman <dan.streetman@canonical.com> Reported-by: Marcin Miroslaw <marcin@mejor.pl> Cc: Seth Jennings <sjenning@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-03 22:13:09 +01:00
static int zswap_enabled_param_set(const char *,
const struct kernel_param *);
static struct kernel_param_ops zswap_enabled_param_ops = {
.set = zswap_enabled_param_set,
.get = param_get_bool,
};
module_param_cb(enabled, &zswap_enabled_param_ops, &zswap_enabled, 0644);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
/* Crypto compressor to use */
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
#define ZSWAP_COMPRESSOR_DEFAULT "lzo"
static char *zswap_compressor = ZSWAP_COMPRESSOR_DEFAULT;
static int zswap_compressor_param_set(const char *,
const struct kernel_param *);
static struct kernel_param_ops zswap_compressor_param_ops = {
.set = zswap_compressor_param_set,
.get = param_get_charp,
.free = param_free_charp,
};
module_param_cb(compressor, &zswap_compressor_param_ops,
&zswap_compressor, 0644);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
/* Compressed storage zpool to use */
#define ZSWAP_ZPOOL_DEFAULT "zbud"
static char *zswap_zpool_type = ZSWAP_ZPOOL_DEFAULT;
static int zswap_zpool_param_set(const char *, const struct kernel_param *);
static struct kernel_param_ops zswap_zpool_param_ops = {
.set = zswap_zpool_param_set,
.get = param_get_charp,
.free = param_free_charp,
};
module_param_cb(zpool, &zswap_zpool_param_ops, &zswap_zpool_type, 0644);
/* The maximum percentage of memory that the compressed pool can occupy */
static unsigned int zswap_max_pool_percent = 20;
module_param_named(max_pool_percent, zswap_max_pool_percent, uint, 0644);
zswap: same-filled pages handling Zswap is a cache which compresses the pages that are being swapped out and stores them into a dynamically allocated RAM-based memory pool. Experiments have shown that around 10-20% of pages stored in zswap are same-filled pages (i.e. contents of the page are all same), but these pages are handled as normal pages by compressing and allocating memory in the pool. This patch adds a check in zswap_frontswap_store() to identify same-filled page before compression of the page. If the page is a same-filled page, set zswap_entry.length to zero, save the same-filled value and skip the compression of the page and alloction of memory in zpool. In zswap_frontswap_load(), check if value of zswap_entry.length is zero corresponding to the page to be loaded. If zswap_entry.length is zero, fill the page with same-filled value. This saves the decompression time during load. On a ARM Quad Core 32-bit device with 1.5GB RAM by launching and relaunching different applications, out of ~64000 pages stored in zswap, ~11000 pages were same-value filled pages (including zero-filled pages) and ~9000 pages were zero-filled pages. An average of 17% of pages(including zero-filled pages) in zswap are same-value filled pages and 14% pages are zero-filled pages. An average of 3% of pages are same-filled non-zero pages. The below table shows the execution time profiling with the patch. Baseline With patch % Improvement ----------------------------------------------------------------- *Zswap Store Time 26.5ms 18ms 32% (of same value pages) *Zswap Load Time (of same value pages) 25.5ms 13ms 49% ----------------------------------------------------------------- On Ubuntu PC with 2GB RAM, while executing kernel build and other test scripts and running multimedia applications, out of 360000 pages stored in zswap 78000(~22%) of pages were found to be same-value filled pages (including zero-filled pages) and 64000(~17%) are zero-filled pages. So an average of %5 of pages are same-filled non-zero pages. The below table shows the execution time profiling with the patch. Baseline With patch % Improvement ----------------------------------------------------------------- *Zswap Store Time 91ms 74ms 19% (of same value pages) *Zswap Load Time 50ms 7.5ms 85% (of same value pages) ----------------------------------------------------------------- *The execution times may vary with test device used. Dan said: : I did test this patch out this week, and I added some instrumentation to : check the performance impact, and tested with a small program to try to : check the best and worst cases. : : When doing a lot of swap where all (or almost all) pages are same-value, I : found this patch does save both time and space, significantly. The exact : improvement in time and space depends on which compressor is being used, : but roughly agrees with the numbers you listed. : : In the worst case situation, where all (or almost all) pages have the : same-value *except* the final long (meaning, zswap will check each long on : the entire page but then still have to pass the page to the compressor), : the same-value check is around 10-15% of the total time spent in : zswap_frontswap_store(). That's a not-insignificant amount of time, but : it's not huge. Considering that most systems will probably be swapping : pages that aren't similar to the worst case (although I don't have any : data to know that), I'd say the improvement is worth the possible : worst-case performance impact. [srividya.dr@samsung.com: add memset_l instead of for loop] Link: http://lkml.kernel.org/r/20171018104832epcms5p1b2232e2236258de3d03d1344dde9fce0@epcms5p1 Signed-off-by: Srividya Desireddy <srividya.dr@samsung.com> Acked-by: Dan Streetman <ddstreet@ieee.org> Cc: Seth Jennings <sjenning@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Dinakar Reddy Pathireddy <dinakar.p@samsung.com> Cc: SHARAN ALLUR <sharan.allur@samsung.com> Cc: RAJIB BASU <rajib.basu@samsung.com> Cc: JUHUN KIM <juhunkim@samsung.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Timofey Titovets <nefelim4ag@gmail.com> Cc: Andi Kleen <ak@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 01:15:59 +01:00
/* Enable/disable handling same-value filled pages (enabled by default) */
static bool zswap_same_filled_pages_enabled = true;
module_param_named(same_filled_pages_enabled, zswap_same_filled_pages_enabled,
bool, 0644);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
/*********************************
* data structures
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
**********************************/
struct zswap_pool {
struct zpool *zpool;
struct crypto_comp * __percpu *tfm;
struct kref kref;
struct list_head list;
mm/zswap: use workqueue to destroy pool Add a work_struct to struct zswap_pool, and change __zswap_pool_empty to use the workqueue instead of using call_rcu(). When zswap destroys a pool no longer in use, it uses call_rcu() to perform the destruction/freeing. Since that executes in softirq context, it must not sleep. However, actually destroying the pool involves freeing the per-cpu compressors (which requires locking the cpu_add_remove_lock mutex) and freeing the zpool, for which the implementation may sleep (e.g. zsmalloc calls kmem_cache_destroy, which locks the slab_mutex). So if either mutex is currently taken, or any other part of the compressor or zpool implementation sleeps, it will result in a BUG(). It's not easy to reproduce this when changing zswap's params normally. In testing with a loaded system, this does not fail: $ cd /sys/module/zswap/parameters $ echo lz4 > compressor ; echo zsmalloc > zpool nor does this: $ while true ; do > echo lzo > compressor ; echo zbud > zpool > sleep 1 > echo lz4 > compressor ; echo zsmalloc > zpool > sleep 1 > done although it's still possible either of those might fail, depending on whether anything else besides zswap has locked the mutexes. However, changing a parameter with no delay immediately causes the schedule while atomic BUG: $ while true ; do > echo lzo > compressor ; echo lz4 > compressor > done This is essentially the same as Yu Zhao's proposed patch to zsmalloc, but moved to zswap, to cover compressor and zpool freeing. Fixes: f1c54846ee45 ("zswap: dynamic pool creation") Signed-off-by: Dan Streetman <ddstreet@ieee.org> Reported-by: Yu Zhao <yuzhao@google.com> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Dan Streetman <dan.streetman@canonical.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-21 01:59:54 +02:00
struct work_struct work;
struct hlist_node node;
char tfm_name[CRYPTO_MAX_ALG_NAME];
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
};
/*
* struct zswap_entry
*
* This structure contains the metadata for tracking a single compressed
* page within zswap.
*
* rbnode - links the entry into red-black tree for the appropriate swap type
* offset - the swap offset for the entry. Index into the red-black tree.
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
* refcount - the number of outstanding reference to the entry. This is needed
* to protect against premature freeing of the entry by code
* concurrent calls to load, invalidate, and writeback. The lock
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
* for the zswap_tree structure that contains the entry must
* be held while changing the refcount. Since the lock must
* be held, there is no reason to also make refcount atomic.
* length - the length in bytes of the compressed page data. Needed during
zswap: same-filled pages handling Zswap is a cache which compresses the pages that are being swapped out and stores them into a dynamically allocated RAM-based memory pool. Experiments have shown that around 10-20% of pages stored in zswap are same-filled pages (i.e. contents of the page are all same), but these pages are handled as normal pages by compressing and allocating memory in the pool. This patch adds a check in zswap_frontswap_store() to identify same-filled page before compression of the page. If the page is a same-filled page, set zswap_entry.length to zero, save the same-filled value and skip the compression of the page and alloction of memory in zpool. In zswap_frontswap_load(), check if value of zswap_entry.length is zero corresponding to the page to be loaded. If zswap_entry.length is zero, fill the page with same-filled value. This saves the decompression time during load. On a ARM Quad Core 32-bit device with 1.5GB RAM by launching and relaunching different applications, out of ~64000 pages stored in zswap, ~11000 pages were same-value filled pages (including zero-filled pages) and ~9000 pages were zero-filled pages. An average of 17% of pages(including zero-filled pages) in zswap are same-value filled pages and 14% pages are zero-filled pages. An average of 3% of pages are same-filled non-zero pages. The below table shows the execution time profiling with the patch. Baseline With patch % Improvement ----------------------------------------------------------------- *Zswap Store Time 26.5ms 18ms 32% (of same value pages) *Zswap Load Time (of same value pages) 25.5ms 13ms 49% ----------------------------------------------------------------- On Ubuntu PC with 2GB RAM, while executing kernel build and other test scripts and running multimedia applications, out of 360000 pages stored in zswap 78000(~22%) of pages were found to be same-value filled pages (including zero-filled pages) and 64000(~17%) are zero-filled pages. So an average of %5 of pages are same-filled non-zero pages. The below table shows the execution time profiling with the patch. Baseline With patch % Improvement ----------------------------------------------------------------- *Zswap Store Time 91ms 74ms 19% (of same value pages) *Zswap Load Time 50ms 7.5ms 85% (of same value pages) ----------------------------------------------------------------- *The execution times may vary with test device used. Dan said: : I did test this patch out this week, and I added some instrumentation to : check the performance impact, and tested with a small program to try to : check the best and worst cases. : : When doing a lot of swap where all (or almost all) pages are same-value, I : found this patch does save both time and space, significantly. The exact : improvement in time and space depends on which compressor is being used, : but roughly agrees with the numbers you listed. : : In the worst case situation, where all (or almost all) pages have the : same-value *except* the final long (meaning, zswap will check each long on : the entire page but then still have to pass the page to the compressor), : the same-value check is around 10-15% of the total time spent in : zswap_frontswap_store(). That's a not-insignificant amount of time, but : it's not huge. Considering that most systems will probably be swapping : pages that aren't similar to the worst case (although I don't have any : data to know that), I'd say the improvement is worth the possible : worst-case performance impact. [srividya.dr@samsung.com: add memset_l instead of for loop] Link: http://lkml.kernel.org/r/20171018104832epcms5p1b2232e2236258de3d03d1344dde9fce0@epcms5p1 Signed-off-by: Srividya Desireddy <srividya.dr@samsung.com> Acked-by: Dan Streetman <ddstreet@ieee.org> Cc: Seth Jennings <sjenning@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Dinakar Reddy Pathireddy <dinakar.p@samsung.com> Cc: SHARAN ALLUR <sharan.allur@samsung.com> Cc: RAJIB BASU <rajib.basu@samsung.com> Cc: JUHUN KIM <juhunkim@samsung.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Timofey Titovets <nefelim4ag@gmail.com> Cc: Andi Kleen <ak@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 01:15:59 +01:00
* decompression. For a same value filled page length is 0.
* pool - the zswap_pool the entry's data is in
* handle - zpool allocation handle that stores the compressed page data
zswap: same-filled pages handling Zswap is a cache which compresses the pages that are being swapped out and stores them into a dynamically allocated RAM-based memory pool. Experiments have shown that around 10-20% of pages stored in zswap are same-filled pages (i.e. contents of the page are all same), but these pages are handled as normal pages by compressing and allocating memory in the pool. This patch adds a check in zswap_frontswap_store() to identify same-filled page before compression of the page. If the page is a same-filled page, set zswap_entry.length to zero, save the same-filled value and skip the compression of the page and alloction of memory in zpool. In zswap_frontswap_load(), check if value of zswap_entry.length is zero corresponding to the page to be loaded. If zswap_entry.length is zero, fill the page with same-filled value. This saves the decompression time during load. On a ARM Quad Core 32-bit device with 1.5GB RAM by launching and relaunching different applications, out of ~64000 pages stored in zswap, ~11000 pages were same-value filled pages (including zero-filled pages) and ~9000 pages were zero-filled pages. An average of 17% of pages(including zero-filled pages) in zswap are same-value filled pages and 14% pages are zero-filled pages. An average of 3% of pages are same-filled non-zero pages. The below table shows the execution time profiling with the patch. Baseline With patch % Improvement ----------------------------------------------------------------- *Zswap Store Time 26.5ms 18ms 32% (of same value pages) *Zswap Load Time (of same value pages) 25.5ms 13ms 49% ----------------------------------------------------------------- On Ubuntu PC with 2GB RAM, while executing kernel build and other test scripts and running multimedia applications, out of 360000 pages stored in zswap 78000(~22%) of pages were found to be same-value filled pages (including zero-filled pages) and 64000(~17%) are zero-filled pages. So an average of %5 of pages are same-filled non-zero pages. The below table shows the execution time profiling with the patch. Baseline With patch % Improvement ----------------------------------------------------------------- *Zswap Store Time 91ms 74ms 19% (of same value pages) *Zswap Load Time 50ms 7.5ms 85% (of same value pages) ----------------------------------------------------------------- *The execution times may vary with test device used. Dan said: : I did test this patch out this week, and I added some instrumentation to : check the performance impact, and tested with a small program to try to : check the best and worst cases. : : When doing a lot of swap where all (or almost all) pages are same-value, I : found this patch does save both time and space, significantly. The exact : improvement in time and space depends on which compressor is being used, : but roughly agrees with the numbers you listed. : : In the worst case situation, where all (or almost all) pages have the : same-value *except* the final long (meaning, zswap will check each long on : the entire page but then still have to pass the page to the compressor), : the same-value check is around 10-15% of the total time spent in : zswap_frontswap_store(). That's a not-insignificant amount of time, but : it's not huge. Considering that most systems will probably be swapping : pages that aren't similar to the worst case (although I don't have any : data to know that), I'd say the improvement is worth the possible : worst-case performance impact. [srividya.dr@samsung.com: add memset_l instead of for loop] Link: http://lkml.kernel.org/r/20171018104832epcms5p1b2232e2236258de3d03d1344dde9fce0@epcms5p1 Signed-off-by: Srividya Desireddy <srividya.dr@samsung.com> Acked-by: Dan Streetman <ddstreet@ieee.org> Cc: Seth Jennings <sjenning@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Dinakar Reddy Pathireddy <dinakar.p@samsung.com> Cc: SHARAN ALLUR <sharan.allur@samsung.com> Cc: RAJIB BASU <rajib.basu@samsung.com> Cc: JUHUN KIM <juhunkim@samsung.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Timofey Titovets <nefelim4ag@gmail.com> Cc: Andi Kleen <ak@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 01:15:59 +01:00
* value - value of the same-value filled pages which have same content
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
*/
struct zswap_entry {
struct rb_node rbnode;
pgoff_t offset;
int refcount;
unsigned int length;
struct zswap_pool *pool;
zswap: same-filled pages handling Zswap is a cache which compresses the pages that are being swapped out and stores them into a dynamically allocated RAM-based memory pool. Experiments have shown that around 10-20% of pages stored in zswap are same-filled pages (i.e. contents of the page are all same), but these pages are handled as normal pages by compressing and allocating memory in the pool. This patch adds a check in zswap_frontswap_store() to identify same-filled page before compression of the page. If the page is a same-filled page, set zswap_entry.length to zero, save the same-filled value and skip the compression of the page and alloction of memory in zpool. In zswap_frontswap_load(), check if value of zswap_entry.length is zero corresponding to the page to be loaded. If zswap_entry.length is zero, fill the page with same-filled value. This saves the decompression time during load. On a ARM Quad Core 32-bit device with 1.5GB RAM by launching and relaunching different applications, out of ~64000 pages stored in zswap, ~11000 pages were same-value filled pages (including zero-filled pages) and ~9000 pages were zero-filled pages. An average of 17% of pages(including zero-filled pages) in zswap are same-value filled pages and 14% pages are zero-filled pages. An average of 3% of pages are same-filled non-zero pages. The below table shows the execution time profiling with the patch. Baseline With patch % Improvement ----------------------------------------------------------------- *Zswap Store Time 26.5ms 18ms 32% (of same value pages) *Zswap Load Time (of same value pages) 25.5ms 13ms 49% ----------------------------------------------------------------- On Ubuntu PC with 2GB RAM, while executing kernel build and other test scripts and running multimedia applications, out of 360000 pages stored in zswap 78000(~22%) of pages were found to be same-value filled pages (including zero-filled pages) and 64000(~17%) are zero-filled pages. So an average of %5 of pages are same-filled non-zero pages. The below table shows the execution time profiling with the patch. Baseline With patch % Improvement ----------------------------------------------------------------- *Zswap Store Time 91ms 74ms 19% (of same value pages) *Zswap Load Time 50ms 7.5ms 85% (of same value pages) ----------------------------------------------------------------- *The execution times may vary with test device used. Dan said: : I did test this patch out this week, and I added some instrumentation to : check the performance impact, and tested with a small program to try to : check the best and worst cases. : : When doing a lot of swap where all (or almost all) pages are same-value, I : found this patch does save both time and space, significantly. The exact : improvement in time and space depends on which compressor is being used, : but roughly agrees with the numbers you listed. : : In the worst case situation, where all (or almost all) pages have the : same-value *except* the final long (meaning, zswap will check each long on : the entire page but then still have to pass the page to the compressor), : the same-value check is around 10-15% of the total time spent in : zswap_frontswap_store(). That's a not-insignificant amount of time, but : it's not huge. Considering that most systems will probably be swapping : pages that aren't similar to the worst case (although I don't have any : data to know that), I'd say the improvement is worth the possible : worst-case performance impact. [srividya.dr@samsung.com: add memset_l instead of for loop] Link: http://lkml.kernel.org/r/20171018104832epcms5p1b2232e2236258de3d03d1344dde9fce0@epcms5p1 Signed-off-by: Srividya Desireddy <srividya.dr@samsung.com> Acked-by: Dan Streetman <ddstreet@ieee.org> Cc: Seth Jennings <sjenning@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Dinakar Reddy Pathireddy <dinakar.p@samsung.com> Cc: SHARAN ALLUR <sharan.allur@samsung.com> Cc: RAJIB BASU <rajib.basu@samsung.com> Cc: JUHUN KIM <juhunkim@samsung.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Timofey Titovets <nefelim4ag@gmail.com> Cc: Andi Kleen <ak@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 01:15:59 +01:00
union {
unsigned long handle;
unsigned long value;
};
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
};
struct zswap_header {
swp_entry_t swpentry;
};
/*
* The tree lock in the zswap_tree struct protects a few things:
* - the rbtree
* - the refcount field of each entry in the tree
*/
struct zswap_tree {
struct rb_root rbroot;
spinlock_t lock;
};
static struct zswap_tree *zswap_trees[MAX_SWAPFILES];
/* RCU-protected iteration */
static LIST_HEAD(zswap_pools);
/* protects zswap_pools list modification */
static DEFINE_SPINLOCK(zswap_pools_lock);
/* pool counter to provide unique names to zpool */
static atomic_t zswap_pools_count = ATOMIC_INIT(0);
/* used by param callback function */
static bool zswap_init_started;
zswap: disable changing params if init fails Add zswap_init_failed bool that prevents changing any of the module params, if init_zswap() fails, and set zswap_enabled to false. Change 'enabled' param to a callback, and check zswap_init_failed before allowing any change to 'enabled', 'zpool', or 'compressor' params. Any driver that is built-in to the kernel will not be unloaded if its init function returns error, and its module params remain accessible for users to change via sysfs. Since zswap uses param callbacks, which assume that zswap has been initialized, changing the zswap params after a failed initialization will result in WARNING due to the param callbacks expecting a pool to already exist. This prevents that by immediately exiting any of the param callbacks if initialization failed. This was reported here: https://marc.info/?l=linux-mm&m=147004228125528&w=4 And fixes this WARNING: [ 429.723476] WARNING: CPU: 0 PID: 5140 at mm/zswap.c:503 __zswap_pool_current+0x56/0x60 The warning is just noise, and not serious. However, when init fails, zswap frees all its percpu dstmem pages and its kmem cache. The kmem cache might be serious, if kmem_cache_alloc(NULL, gfp) has problems; but the percpu dstmem pages are definitely a problem, as they're used as temporary buffer for compressed pages before copying into place in the zpool. If the user does get zswap enabled after an init failure, then zswap will likely Oops on the first page it tries to compress (or worse, start corrupting memory). Fixes: 90b0fc26d5db ("zswap: change zpool/compressor at runtime") Link: http://lkml.kernel.org/r/20170124200259.16191-2-ddstreet@ieee.org Signed-off-by: Dan Streetman <dan.streetman@canonical.com> Reported-by: Marcin Miroslaw <marcin@mejor.pl> Cc: Seth Jennings <sjenning@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-03 22:13:09 +01:00
/* fatal error during init */
static bool zswap_init_failed;
/* init completed, but couldn't create the initial pool */
static bool zswap_has_pool;
/*********************************
* helpers and fwd declarations
**********************************/
#define zswap_pool_debug(msg, p) \
pr_debug("%s pool %s/%s\n", msg, (p)->tfm_name, \
zpool_get_type((p)->zpool))
static int zswap_writeback_entry(struct zpool *pool, unsigned long handle);
static int zswap_pool_get(struct zswap_pool *pool);
static void zswap_pool_put(struct zswap_pool *pool);
static const struct zpool_ops zswap_zpool_ops = {
.evict = zswap_writeback_entry
};
static bool zswap_is_full(void)
{
return totalram_pages * zswap_max_pool_percent / 100 <
DIV_ROUND_UP(zswap_pool_total_size, PAGE_SIZE);
}
static void zswap_update_total_size(void)
{
struct zswap_pool *pool;
u64 total = 0;
rcu_read_lock();
list_for_each_entry_rcu(pool, &zswap_pools, list)
total += zpool_get_total_size(pool->zpool);
rcu_read_unlock();
zswap_pool_total_size = total;
}
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
/*********************************
* zswap entry functions
**********************************/
static struct kmem_cache *zswap_entry_cache;
static int __init zswap_entry_cache_create(void)
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
{
zswap_entry_cache = KMEM_CACHE(zswap_entry, 0);
return zswap_entry_cache == NULL;
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
}
static void __init zswap_entry_cache_destroy(void)
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
{
kmem_cache_destroy(zswap_entry_cache);
}
static struct zswap_entry *zswap_entry_cache_alloc(gfp_t gfp)
{
struct zswap_entry *entry;
entry = kmem_cache_alloc(zswap_entry_cache, gfp);
if (!entry)
return NULL;
entry->refcount = 1;
RB_CLEAR_NODE(&entry->rbnode);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
return entry;
}
static void zswap_entry_cache_free(struct zswap_entry *entry)
{
kmem_cache_free(zswap_entry_cache, entry);
}
/*********************************
* rbtree functions
**********************************/
static struct zswap_entry *zswap_rb_search(struct rb_root *root, pgoff_t offset)
{
struct rb_node *node = root->rb_node;
struct zswap_entry *entry;
while (node) {
entry = rb_entry(node, struct zswap_entry, rbnode);
if (entry->offset > offset)
node = node->rb_left;
else if (entry->offset < offset)
node = node->rb_right;
else
return entry;
}
return NULL;
}
/*
* In the case that a entry with the same offset is found, a pointer to
* the existing entry is stored in dupentry and the function returns -EEXIST
*/
static int zswap_rb_insert(struct rb_root *root, struct zswap_entry *entry,
struct zswap_entry **dupentry)
{
struct rb_node **link = &root->rb_node, *parent = NULL;
struct zswap_entry *myentry;
while (*link) {
parent = *link;
myentry = rb_entry(parent, struct zswap_entry, rbnode);
if (myentry->offset > entry->offset)
link = &(*link)->rb_left;
else if (myentry->offset < entry->offset)
link = &(*link)->rb_right;
else {
*dupentry = myentry;
return -EEXIST;
}
}
rb_link_node(&entry->rbnode, parent, link);
rb_insert_color(&entry->rbnode, root);
return 0;
}
static void zswap_rb_erase(struct rb_root *root, struct zswap_entry *entry)
{
if (!RB_EMPTY_NODE(&entry->rbnode)) {
rb_erase(&entry->rbnode, root);
RB_CLEAR_NODE(&entry->rbnode);
}
}
/*
* Carries out the common pattern of freeing and entry's zpool allocation,
* freeing the entry itself, and decrementing the number of stored pages.
*/
static void zswap_free_entry(struct zswap_entry *entry)
{
zswap: same-filled pages handling Zswap is a cache which compresses the pages that are being swapped out and stores them into a dynamically allocated RAM-based memory pool. Experiments have shown that around 10-20% of pages stored in zswap are same-filled pages (i.e. contents of the page are all same), but these pages are handled as normal pages by compressing and allocating memory in the pool. This patch adds a check in zswap_frontswap_store() to identify same-filled page before compression of the page. If the page is a same-filled page, set zswap_entry.length to zero, save the same-filled value and skip the compression of the page and alloction of memory in zpool. In zswap_frontswap_load(), check if value of zswap_entry.length is zero corresponding to the page to be loaded. If zswap_entry.length is zero, fill the page with same-filled value. This saves the decompression time during load. On a ARM Quad Core 32-bit device with 1.5GB RAM by launching and relaunching different applications, out of ~64000 pages stored in zswap, ~11000 pages were same-value filled pages (including zero-filled pages) and ~9000 pages were zero-filled pages. An average of 17% of pages(including zero-filled pages) in zswap are same-value filled pages and 14% pages are zero-filled pages. An average of 3% of pages are same-filled non-zero pages. The below table shows the execution time profiling with the patch. Baseline With patch % Improvement ----------------------------------------------------------------- *Zswap Store Time 26.5ms 18ms 32% (of same value pages) *Zswap Load Time (of same value pages) 25.5ms 13ms 49% ----------------------------------------------------------------- On Ubuntu PC with 2GB RAM, while executing kernel build and other test scripts and running multimedia applications, out of 360000 pages stored in zswap 78000(~22%) of pages were found to be same-value filled pages (including zero-filled pages) and 64000(~17%) are zero-filled pages. So an average of %5 of pages are same-filled non-zero pages. The below table shows the execution time profiling with the patch. Baseline With patch % Improvement ----------------------------------------------------------------- *Zswap Store Time 91ms 74ms 19% (of same value pages) *Zswap Load Time 50ms 7.5ms 85% (of same value pages) ----------------------------------------------------------------- *The execution times may vary with test device used. Dan said: : I did test this patch out this week, and I added some instrumentation to : check the performance impact, and tested with a small program to try to : check the best and worst cases. : : When doing a lot of swap where all (or almost all) pages are same-value, I : found this patch does save both time and space, significantly. The exact : improvement in time and space depends on which compressor is being used, : but roughly agrees with the numbers you listed. : : In the worst case situation, where all (or almost all) pages have the : same-value *except* the final long (meaning, zswap will check each long on : the entire page but then still have to pass the page to the compressor), : the same-value check is around 10-15% of the total time spent in : zswap_frontswap_store(). That's a not-insignificant amount of time, but : it's not huge. Considering that most systems will probably be swapping : pages that aren't similar to the worst case (although I don't have any : data to know that), I'd say the improvement is worth the possible : worst-case performance impact. [srividya.dr@samsung.com: add memset_l instead of for loop] Link: http://lkml.kernel.org/r/20171018104832epcms5p1b2232e2236258de3d03d1344dde9fce0@epcms5p1 Signed-off-by: Srividya Desireddy <srividya.dr@samsung.com> Acked-by: Dan Streetman <ddstreet@ieee.org> Cc: Seth Jennings <sjenning@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Dinakar Reddy Pathireddy <dinakar.p@samsung.com> Cc: SHARAN ALLUR <sharan.allur@samsung.com> Cc: RAJIB BASU <rajib.basu@samsung.com> Cc: JUHUN KIM <juhunkim@samsung.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Timofey Titovets <nefelim4ag@gmail.com> Cc: Andi Kleen <ak@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 01:15:59 +01:00
if (!entry->length)
atomic_dec(&zswap_same_filled_pages);
else {
zpool_free(entry->pool->zpool, entry->handle);
zswap_pool_put(entry->pool);
}
zswap_entry_cache_free(entry);
atomic_dec(&zswap_stored_pages);
zswap_update_total_size();
}
/* caller must hold the tree lock */
static void zswap_entry_get(struct zswap_entry *entry)
{
entry->refcount++;
}
/* caller must hold the tree lock
* remove from the tree and free it, if nobody reference the entry
*/
static void zswap_entry_put(struct zswap_tree *tree,
struct zswap_entry *entry)
{
int refcount = --entry->refcount;
BUG_ON(refcount < 0);
if (refcount == 0) {
zswap_rb_erase(&tree->rbroot, entry);
zswap_free_entry(entry);
}
}
/* caller must hold the tree lock */
static struct zswap_entry *zswap_entry_find_get(struct rb_root *root,
pgoff_t offset)
{
struct zswap_entry *entry;
entry = zswap_rb_search(root, offset);
if (entry)
zswap_entry_get(entry);
return entry;
}
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
/*********************************
* per-cpu code
**********************************/
static DEFINE_PER_CPU(u8 *, zswap_dstmem);
static int zswap_dstmem_prepare(unsigned int cpu)
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
{
u8 *dst;
dst = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
if (!dst)
return -ENOMEM;
per_cpu(zswap_dstmem, cpu) = dst;
return 0;
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
}
static int zswap_dstmem_dead(unsigned int cpu)
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
{
u8 *dst;
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
dst = per_cpu(zswap_dstmem, cpu);
kfree(dst);
per_cpu(zswap_dstmem, cpu) = NULL;
return 0;
}
static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
{
struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
struct crypto_comp *tfm;
if (WARN_ON(*per_cpu_ptr(pool->tfm, cpu)))
return 0;
tfm = crypto_alloc_comp(pool->tfm_name, 0, 0);
if (IS_ERR_OR_NULL(tfm)) {
pr_err("could not alloc crypto comp %s : %ld\n",
pool->tfm_name, PTR_ERR(tfm));
return -ENOMEM;
}
*per_cpu_ptr(pool->tfm, cpu) = tfm;
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
return 0;
}
static int zswap_cpu_comp_dead(unsigned int cpu, struct hlist_node *node)
{
struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
struct crypto_comp *tfm;
tfm = *per_cpu_ptr(pool->tfm, cpu);
if (!IS_ERR_OR_NULL(tfm))
crypto_free_comp(tfm);
*per_cpu_ptr(pool->tfm, cpu) = NULL;
return 0;
}
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
/*********************************
* pool functions
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
**********************************/
static struct zswap_pool *__zswap_pool_current(void)
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
{
struct zswap_pool *pool;
pool = list_first_or_null_rcu(&zswap_pools, typeof(*pool), list);
WARN_ONCE(!pool && zswap_has_pool,
"%s: no page storage pool!\n", __func__);
return pool;
}
static struct zswap_pool *zswap_pool_current(void)
{
assert_spin_locked(&zswap_pools_lock);
return __zswap_pool_current();
}
static struct zswap_pool *zswap_pool_current_get(void)
{
struct zswap_pool *pool;
rcu_read_lock();
pool = __zswap_pool_current();
if (!zswap_pool_get(pool))
pool = NULL;
rcu_read_unlock();
return pool;
}
static struct zswap_pool *zswap_pool_last_get(void)
{
struct zswap_pool *pool, *last = NULL;
rcu_read_lock();
list_for_each_entry_rcu(pool, &zswap_pools, list)
last = pool;
WARN_ONCE(!last && zswap_has_pool,
"%s: no page storage pool!\n", __func__);
if (!zswap_pool_get(last))
last = NULL;
rcu_read_unlock();
return last;
}
/* type and compressor must be null-terminated */
static struct zswap_pool *zswap_pool_find_get(char *type, char *compressor)
{
struct zswap_pool *pool;
assert_spin_locked(&zswap_pools_lock);
list_for_each_entry_rcu(pool, &zswap_pools, list) {
if (strcmp(pool->tfm_name, compressor))
continue;
if (strcmp(zpool_get_type(pool->zpool), type))
continue;
/* if we can't get it, it's about to be destroyed */
if (!zswap_pool_get(pool))
continue;
return pool;
}
return NULL;
}
static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
{
struct zswap_pool *pool;
char name[38]; /* 'zswap' + 32 char (max) num + \0 */
mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd __GFP_WAIT has been used to identify atomic context in callers that hold spinlocks or are in interrupts. They are expected to be high priority and have access one of two watermarks lower than "min" which can be referred to as the "atomic reserve". __GFP_HIGH users get access to the first lower watermark and can be called the "high priority reserve". Over time, callers had a requirement to not block when fallback options were available. Some have abused __GFP_WAIT leading to a situation where an optimisitic allocation with a fallback option can access atomic reserves. This patch uses __GFP_ATOMIC to identify callers that are truely atomic, cannot sleep and have no alternative. High priority users continue to use __GFP_HIGH. __GFP_DIRECT_RECLAIM identifies callers that can sleep and are willing to enter direct reclaim. __GFP_KSWAPD_RECLAIM to identify callers that want to wake kswapd for background reclaim. __GFP_WAIT is redefined as a caller that is willing to enter direct reclaim and wake kswapd for background reclaim. This patch then converts a number of sites o __GFP_ATOMIC is used by callers that are high priority and have memory pools for those requests. GFP_ATOMIC uses this flag. o Callers that have a limited mempool to guarantee forward progress clear __GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall into this category where kswapd will still be woken but atomic reserves are not used as there is a one-entry mempool to guarantee progress. o Callers that are checking if they are non-blocking should use the helper gfpflags_allow_blocking() where possible. This is because checking for __GFP_WAIT as was done historically now can trigger false positives. Some exceptions like dm-crypt.c exist where the code intent is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to flag manipulations. o Callers that built their own GFP flags instead of starting with GFP_KERNEL and friends now also need to specify __GFP_KSWAPD_RECLAIM. The first key hazard to watch out for is callers that removed __GFP_WAIT and was depending on access to atomic reserves for inconspicuous reasons. In some cases it may be appropriate for them to use __GFP_HIGH. The second key hazard is callers that assembled their own combination of GFP flags instead of starting with something like GFP_KERNEL. They may now wish to specify __GFP_KSWAPD_RECLAIM. It's almost certainly harmless if it's missed in most cases as other activity will wake kswapd. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-07 01:28:21 +01:00
gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM;
int ret;
if (!zswap_has_pool) {
/* if either are unset, pool initialization failed, and we
* need both params to be set correctly before trying to
* create a pool.
*/
if (!strcmp(type, ZSWAP_PARAM_UNSET))
return NULL;
if (!strcmp(compressor, ZSWAP_PARAM_UNSET))
return NULL;
}
pool = kzalloc(sizeof(*pool), GFP_KERNEL);
if (!pool)
return NULL;
/* unique name for each pool specifically required by zsmalloc */
snprintf(name, 38, "zswap%x", atomic_inc_return(&zswap_pools_count));
pool->zpool = zpool_create_pool(type, name, gfp, &zswap_zpool_ops);
if (!pool->zpool) {
pr_err("%s zpool not available\n", type);
goto error;
}
pr_debug("using %s zpool\n", zpool_get_type(pool->zpool));
strlcpy(pool->tfm_name, compressor, sizeof(pool->tfm_name));
pool->tfm = alloc_percpu(struct crypto_comp *);
if (!pool->tfm) {
pr_err("percpu alloc failed\n");
goto error;
}
ret = cpuhp_state_add_instance(CPUHP_MM_ZSWP_POOL_PREPARE,
&pool->node);
if (ret)
goto error;
pr_debug("using %s compressor\n", pool->tfm_name);
/* being the current pool takes 1 ref; this func expects the
* caller to always add the new pool as the current pool
*/
kref_init(&pool->kref);
INIT_LIST_HEAD(&pool->list);
zswap_pool_debug("created", pool);
return pool;
error:
free_percpu(pool->tfm);
if (pool->zpool)
zpool_destroy_pool(pool->zpool);
kfree(pool);
return NULL;
}
static __init struct zswap_pool *__zswap_pool_create_fallback(void)
{
bool has_comp, has_zpool;
has_comp = crypto_has_comp(zswap_compressor, 0, 0);
if (!has_comp && strcmp(zswap_compressor, ZSWAP_COMPRESSOR_DEFAULT)) {
pr_err("compressor %s not available, using default %s\n",
zswap_compressor, ZSWAP_COMPRESSOR_DEFAULT);
param_free_charp(&zswap_compressor);
zswap_compressor = ZSWAP_COMPRESSOR_DEFAULT;
has_comp = crypto_has_comp(zswap_compressor, 0, 0);
}
if (!has_comp) {
pr_err("default compressor %s not available\n",
zswap_compressor);
param_free_charp(&zswap_compressor);
zswap_compressor = ZSWAP_PARAM_UNSET;
}
has_zpool = zpool_has_pool(zswap_zpool_type);
if (!has_zpool && strcmp(zswap_zpool_type, ZSWAP_ZPOOL_DEFAULT)) {
pr_err("zpool %s not available, using default %s\n",
zswap_zpool_type, ZSWAP_ZPOOL_DEFAULT);
param_free_charp(&zswap_zpool_type);
zswap_zpool_type = ZSWAP_ZPOOL_DEFAULT;
has_zpool = zpool_has_pool(zswap_zpool_type);
}
if (!has_zpool) {
pr_err("default zpool %s not available\n",
zswap_zpool_type);
param_free_charp(&zswap_zpool_type);
zswap_zpool_type = ZSWAP_PARAM_UNSET;
}
if (!has_comp || !has_zpool)
return NULL;
return zswap_pool_create(zswap_zpool_type, zswap_compressor);
}
static void zswap_pool_destroy(struct zswap_pool *pool)
{
zswap_pool_debug("destroying", pool);
cpuhp_state_remove_instance(CPUHP_MM_ZSWP_POOL_PREPARE, &pool->node);
free_percpu(pool->tfm);
zpool_destroy_pool(pool->zpool);
kfree(pool);
}
static int __must_check zswap_pool_get(struct zswap_pool *pool)
{
if (!pool)
return 0;
return kref_get_unless_zero(&pool->kref);
}
mm/zswap: use workqueue to destroy pool Add a work_struct to struct zswap_pool, and change __zswap_pool_empty to use the workqueue instead of using call_rcu(). When zswap destroys a pool no longer in use, it uses call_rcu() to perform the destruction/freeing. Since that executes in softirq context, it must not sleep. However, actually destroying the pool involves freeing the per-cpu compressors (which requires locking the cpu_add_remove_lock mutex) and freeing the zpool, for which the implementation may sleep (e.g. zsmalloc calls kmem_cache_destroy, which locks the slab_mutex). So if either mutex is currently taken, or any other part of the compressor or zpool implementation sleeps, it will result in a BUG(). It's not easy to reproduce this when changing zswap's params normally. In testing with a loaded system, this does not fail: $ cd /sys/module/zswap/parameters $ echo lz4 > compressor ; echo zsmalloc > zpool nor does this: $ while true ; do > echo lzo > compressor ; echo zbud > zpool > sleep 1 > echo lz4 > compressor ; echo zsmalloc > zpool > sleep 1 > done although it's still possible either of those might fail, depending on whether anything else besides zswap has locked the mutexes. However, changing a parameter with no delay immediately causes the schedule while atomic BUG: $ while true ; do > echo lzo > compressor ; echo lz4 > compressor > done This is essentially the same as Yu Zhao's proposed patch to zsmalloc, but moved to zswap, to cover compressor and zpool freeing. Fixes: f1c54846ee45 ("zswap: dynamic pool creation") Signed-off-by: Dan Streetman <ddstreet@ieee.org> Reported-by: Yu Zhao <yuzhao@google.com> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Dan Streetman <dan.streetman@canonical.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-21 01:59:54 +02:00
static void __zswap_pool_release(struct work_struct *work)
{
mm/zswap: use workqueue to destroy pool Add a work_struct to struct zswap_pool, and change __zswap_pool_empty to use the workqueue instead of using call_rcu(). When zswap destroys a pool no longer in use, it uses call_rcu() to perform the destruction/freeing. Since that executes in softirq context, it must not sleep. However, actually destroying the pool involves freeing the per-cpu compressors (which requires locking the cpu_add_remove_lock mutex) and freeing the zpool, for which the implementation may sleep (e.g. zsmalloc calls kmem_cache_destroy, which locks the slab_mutex). So if either mutex is currently taken, or any other part of the compressor or zpool implementation sleeps, it will result in a BUG(). It's not easy to reproduce this when changing zswap's params normally. In testing with a loaded system, this does not fail: $ cd /sys/module/zswap/parameters $ echo lz4 > compressor ; echo zsmalloc > zpool nor does this: $ while true ; do > echo lzo > compressor ; echo zbud > zpool > sleep 1 > echo lz4 > compressor ; echo zsmalloc > zpool > sleep 1 > done although it's still possible either of those might fail, depending on whether anything else besides zswap has locked the mutexes. However, changing a parameter with no delay immediately causes the schedule while atomic BUG: $ while true ; do > echo lzo > compressor ; echo lz4 > compressor > done This is essentially the same as Yu Zhao's proposed patch to zsmalloc, but moved to zswap, to cover compressor and zpool freeing. Fixes: f1c54846ee45 ("zswap: dynamic pool creation") Signed-off-by: Dan Streetman <ddstreet@ieee.org> Reported-by: Yu Zhao <yuzhao@google.com> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Dan Streetman <dan.streetman@canonical.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-21 01:59:54 +02:00
struct zswap_pool *pool = container_of(work, typeof(*pool), work);
synchronize_rcu();
/* nobody should have been able to get a kref... */
WARN_ON(kref_get_unless_zero(&pool->kref));
/* pool is now off zswap_pools list and has no references. */
zswap_pool_destroy(pool);
}
static void __zswap_pool_empty(struct kref *kref)
{
struct zswap_pool *pool;
pool = container_of(kref, typeof(*pool), kref);
spin_lock(&zswap_pools_lock);
WARN_ON(pool == zswap_pool_current());
list_del_rcu(&pool->list);
mm/zswap: use workqueue to destroy pool Add a work_struct to struct zswap_pool, and change __zswap_pool_empty to use the workqueue instead of using call_rcu(). When zswap destroys a pool no longer in use, it uses call_rcu() to perform the destruction/freeing. Since that executes in softirq context, it must not sleep. However, actually destroying the pool involves freeing the per-cpu compressors (which requires locking the cpu_add_remove_lock mutex) and freeing the zpool, for which the implementation may sleep (e.g. zsmalloc calls kmem_cache_destroy, which locks the slab_mutex). So if either mutex is currently taken, or any other part of the compressor or zpool implementation sleeps, it will result in a BUG(). It's not easy to reproduce this when changing zswap's params normally. In testing with a loaded system, this does not fail: $ cd /sys/module/zswap/parameters $ echo lz4 > compressor ; echo zsmalloc > zpool nor does this: $ while true ; do > echo lzo > compressor ; echo zbud > zpool > sleep 1 > echo lz4 > compressor ; echo zsmalloc > zpool > sleep 1 > done although it's still possible either of those might fail, depending on whether anything else besides zswap has locked the mutexes. However, changing a parameter with no delay immediately causes the schedule while atomic BUG: $ while true ; do > echo lzo > compressor ; echo lz4 > compressor > done This is essentially the same as Yu Zhao's proposed patch to zsmalloc, but moved to zswap, to cover compressor and zpool freeing. Fixes: f1c54846ee45 ("zswap: dynamic pool creation") Signed-off-by: Dan Streetman <ddstreet@ieee.org> Reported-by: Yu Zhao <yuzhao@google.com> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Dan Streetman <dan.streetman@canonical.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-21 01:59:54 +02:00
INIT_WORK(&pool->work, __zswap_pool_release);
schedule_work(&pool->work);
spin_unlock(&zswap_pools_lock);
}
static void zswap_pool_put(struct zswap_pool *pool)
{
kref_put(&pool->kref, __zswap_pool_empty);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
}
/*********************************
* param callbacks
**********************************/
/* val must be a null-terminated string */
static int __zswap_param_set(const char *val, const struct kernel_param *kp,
char *type, char *compressor)
{
struct zswap_pool *pool, *put_pool = NULL;
char *s = strstrip((char *)val);
int ret;
zswap: disable changing params if init fails Add zswap_init_failed bool that prevents changing any of the module params, if init_zswap() fails, and set zswap_enabled to false. Change 'enabled' param to a callback, and check zswap_init_failed before allowing any change to 'enabled', 'zpool', or 'compressor' params. Any driver that is built-in to the kernel will not be unloaded if its init function returns error, and its module params remain accessible for users to change via sysfs. Since zswap uses param callbacks, which assume that zswap has been initialized, changing the zswap params after a failed initialization will result in WARNING due to the param callbacks expecting a pool to already exist. This prevents that by immediately exiting any of the param callbacks if initialization failed. This was reported here: https://marc.info/?l=linux-mm&m=147004228125528&w=4 And fixes this WARNING: [ 429.723476] WARNING: CPU: 0 PID: 5140 at mm/zswap.c:503 __zswap_pool_current+0x56/0x60 The warning is just noise, and not serious. However, when init fails, zswap frees all its percpu dstmem pages and its kmem cache. The kmem cache might be serious, if kmem_cache_alloc(NULL, gfp) has problems; but the percpu dstmem pages are definitely a problem, as they're used as temporary buffer for compressed pages before copying into place in the zpool. If the user does get zswap enabled after an init failure, then zswap will likely Oops on the first page it tries to compress (or worse, start corrupting memory). Fixes: 90b0fc26d5db ("zswap: change zpool/compressor at runtime") Link: http://lkml.kernel.org/r/20170124200259.16191-2-ddstreet@ieee.org Signed-off-by: Dan Streetman <dan.streetman@canonical.com> Reported-by: Marcin Miroslaw <marcin@mejor.pl> Cc: Seth Jennings <sjenning@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-03 22:13:09 +01:00
if (zswap_init_failed) {
pr_err("can't set param, initialization failed\n");
return -ENODEV;
}
/* no change required */
if (!strcmp(s, *(char **)kp->arg) && zswap_has_pool)
return 0;
/* if this is load-time (pre-init) param setting,
* don't create a pool; that's done during init.
*/
if (!zswap_init_started)
return param_set_charp(s, kp);
if (!type) {
if (!zpool_has_pool(s)) {
pr_err("zpool %s not available\n", s);
return -ENOENT;
}
type = s;
} else if (!compressor) {
if (!crypto_has_comp(s, 0, 0)) {
pr_err("compressor %s not available\n", s);
return -ENOENT;
}
compressor = s;
} else {
WARN_ON(1);
return -EINVAL;
}
spin_lock(&zswap_pools_lock);
pool = zswap_pool_find_get(type, compressor);
if (pool) {
zswap_pool_debug("using existing", pool);
WARN_ON(pool == zswap_pool_current());
list_del_rcu(&pool->list);
}
spin_unlock(&zswap_pools_lock);
if (!pool)
pool = zswap_pool_create(type, compressor);
if (pool)
ret = param_set_charp(s, kp);
else
ret = -EINVAL;
spin_lock(&zswap_pools_lock);
if (!ret) {
put_pool = zswap_pool_current();
list_add_rcu(&pool->list, &zswap_pools);
zswap_has_pool = true;
} else if (pool) {
/* add the possibly pre-existing pool to the end of the pools
* list; if it's new (and empty) then it'll be removed and
* destroyed by the put after we drop the lock
*/
list_add_tail_rcu(&pool->list, &zswap_pools);
put_pool = pool;
}
spin_unlock(&zswap_pools_lock);
if (!zswap_has_pool && !pool) {
/* if initial pool creation failed, and this pool creation also
* failed, maybe both compressor and zpool params were bad.
* Allow changing this param, so pool creation will succeed
* when the other param is changed. We already verified this
* param is ok in the zpool_has_pool() or crypto_has_comp()
* checks above.
*/
ret = param_set_charp(s, kp);
}
/* drop the ref from either the old current pool,
* or the new pool we failed to add
*/
if (put_pool)
zswap_pool_put(put_pool);
return ret;
}
static int zswap_compressor_param_set(const char *val,
const struct kernel_param *kp)
{
return __zswap_param_set(val, kp, zswap_zpool_type, NULL);
}
static int zswap_zpool_param_set(const char *val,
const struct kernel_param *kp)
{
return __zswap_param_set(val, kp, NULL, zswap_compressor);
}
zswap: disable changing params if init fails Add zswap_init_failed bool that prevents changing any of the module params, if init_zswap() fails, and set zswap_enabled to false. Change 'enabled' param to a callback, and check zswap_init_failed before allowing any change to 'enabled', 'zpool', or 'compressor' params. Any driver that is built-in to the kernel will not be unloaded if its init function returns error, and its module params remain accessible for users to change via sysfs. Since zswap uses param callbacks, which assume that zswap has been initialized, changing the zswap params after a failed initialization will result in WARNING due to the param callbacks expecting a pool to already exist. This prevents that by immediately exiting any of the param callbacks if initialization failed. This was reported here: https://marc.info/?l=linux-mm&m=147004228125528&w=4 And fixes this WARNING: [ 429.723476] WARNING: CPU: 0 PID: 5140 at mm/zswap.c:503 __zswap_pool_current+0x56/0x60 The warning is just noise, and not serious. However, when init fails, zswap frees all its percpu dstmem pages and its kmem cache. The kmem cache might be serious, if kmem_cache_alloc(NULL, gfp) has problems; but the percpu dstmem pages are definitely a problem, as they're used as temporary buffer for compressed pages before copying into place in the zpool. If the user does get zswap enabled after an init failure, then zswap will likely Oops on the first page it tries to compress (or worse, start corrupting memory). Fixes: 90b0fc26d5db ("zswap: change zpool/compressor at runtime") Link: http://lkml.kernel.org/r/20170124200259.16191-2-ddstreet@ieee.org Signed-off-by: Dan Streetman <dan.streetman@canonical.com> Reported-by: Marcin Miroslaw <marcin@mejor.pl> Cc: Seth Jennings <sjenning@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-03 22:13:09 +01:00
static int zswap_enabled_param_set(const char *val,
const struct kernel_param *kp)
{
if (zswap_init_failed) {
pr_err("can't enable, initialization failed\n");
return -ENODEV;
}
if (!zswap_has_pool && zswap_init_started) {
pr_err("can't enable, no pool configured\n");
return -ENODEV;
}
zswap: disable changing params if init fails Add zswap_init_failed bool that prevents changing any of the module params, if init_zswap() fails, and set zswap_enabled to false. Change 'enabled' param to a callback, and check zswap_init_failed before allowing any change to 'enabled', 'zpool', or 'compressor' params. Any driver that is built-in to the kernel will not be unloaded if its init function returns error, and its module params remain accessible for users to change via sysfs. Since zswap uses param callbacks, which assume that zswap has been initialized, changing the zswap params after a failed initialization will result in WARNING due to the param callbacks expecting a pool to already exist. This prevents that by immediately exiting any of the param callbacks if initialization failed. This was reported here: https://marc.info/?l=linux-mm&m=147004228125528&w=4 And fixes this WARNING: [ 429.723476] WARNING: CPU: 0 PID: 5140 at mm/zswap.c:503 __zswap_pool_current+0x56/0x60 The warning is just noise, and not serious. However, when init fails, zswap frees all its percpu dstmem pages and its kmem cache. The kmem cache might be serious, if kmem_cache_alloc(NULL, gfp) has problems; but the percpu dstmem pages are definitely a problem, as they're used as temporary buffer for compressed pages before copying into place in the zpool. If the user does get zswap enabled after an init failure, then zswap will likely Oops on the first page it tries to compress (or worse, start corrupting memory). Fixes: 90b0fc26d5db ("zswap: change zpool/compressor at runtime") Link: http://lkml.kernel.org/r/20170124200259.16191-2-ddstreet@ieee.org Signed-off-by: Dan Streetman <dan.streetman@canonical.com> Reported-by: Marcin Miroslaw <marcin@mejor.pl> Cc: Seth Jennings <sjenning@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-03 22:13:09 +01:00
return param_set_bool(val, kp);
}
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
/*********************************
* writeback code
**********************************/
/* return enum for zswap_get_swap_cache_page */
enum zswap_get_swap_ret {
ZSWAP_SWAPCACHE_NEW,
ZSWAP_SWAPCACHE_EXIST,
ZSWAP_SWAPCACHE_FAIL,
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
};
/*
* zswap_get_swap_cache_page
*
* This is an adaption of read_swap_cache_async()
*
* This function tries to find a page with the given swap entry
* in the swapper_space address space (the swap cache). If the page
* is found, it is returned in retpage. Otherwise, a page is allocated,
* added to the swap cache, and returned in retpage.
*
* If success, the swap cache page is returned in retpage
* Returns ZSWAP_SWAPCACHE_EXIST if page was already in the swap cache
* Returns ZSWAP_SWAPCACHE_NEW if the new page needs to be populated,
* the new page is added to swapcache and locked
* Returns ZSWAP_SWAPCACHE_FAIL on error
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
*/
static int zswap_get_swap_cache_page(swp_entry_t entry,
struct page **retpage)
{
bool page_was_allocated;
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
*retpage = __read_swap_cache_async(entry, GFP_KERNEL,
NULL, 0, &page_was_allocated);
if (page_was_allocated)
return ZSWAP_SWAPCACHE_NEW;
if (!*retpage)
return ZSWAP_SWAPCACHE_FAIL;
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
return ZSWAP_SWAPCACHE_EXIST;
}
/*
* Attempts to free an entry by adding a page to the swap cache,
* decompressing the entry data into the page, and issuing a
* bio write to write the page back to the swap device.
*
* This can be thought of as a "resumed writeback" of the page
* to the swap device. We are basically resuming the same swap
* writeback path that was intercepted with the frontswap_store()
* in the first place. After the page has been decompressed into
* the swap cache, the compressed version stored by zswap can be
* freed.
*/
static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
{
struct zswap_header *zhdr;
swp_entry_t swpentry;
struct zswap_tree *tree;
pgoff_t offset;
struct zswap_entry *entry;
struct page *page;
struct crypto_comp *tfm;
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
u8 *src, *dst;
unsigned int dlen;
int ret;
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
struct writeback_control wbc = {
.sync_mode = WB_SYNC_NONE,
};
/* extract swpentry from data */
zhdr = zpool_map_handle(pool, handle, ZPOOL_MM_RO);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
swpentry = zhdr->swpentry; /* here */
zpool_unmap_handle(pool, handle);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
tree = zswap_trees[swp_type(swpentry)];
offset = swp_offset(swpentry);
/* find and ref zswap entry */
spin_lock(&tree->lock);
entry = zswap_entry_find_get(&tree->rbroot, offset);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
if (!entry) {
/* entry was invalidated */
spin_unlock(&tree->lock);
return 0;
}
spin_unlock(&tree->lock);
BUG_ON(offset != entry->offset);
/* try to allocate swap cache page */
switch (zswap_get_swap_cache_page(swpentry, &page)) {
case ZSWAP_SWAPCACHE_FAIL: /* no memory or invalidate happened */
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
ret = -ENOMEM;
goto fail;
case ZSWAP_SWAPCACHE_EXIST:
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
/* page is already in the swap cache, ignore for now */
mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time ago with promise that one day it will be possible to implement page cache with bigger chunks than PAGE_SIZE. This promise never materialized. And unlikely will. We have many places where PAGE_CACHE_SIZE assumed to be equal to PAGE_SIZE. And it's constant source of confusion on whether PAGE_CACHE_* or PAGE_* constant should be used in a particular case, especially on the border between fs and mm. Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much breakage to be doable. Let's stop pretending that pages in page cache are special. They are not. The changes are pretty straight-forward: - <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN}; - page_cache_get() -> get_page(); - page_cache_release() -> put_page(); This patch contains automated changes generated with coccinelle using script below. For some reason, coccinelle doesn't patch header files. I've called spatch for them manually. The only adjustment after coccinelle is revert of changes to PAGE_CAHCE_ALIGN definition: we are going to drop it later. There are few places in the code where coccinelle didn't reach. I'll fix them manually in a separate patch. Comments and documentation also will be addressed with the separate patch. virtual patch @@ expression E; @@ - E << (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ expression E; @@ - E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ @@ - PAGE_CACHE_SHIFT + PAGE_SHIFT @@ @@ - PAGE_CACHE_SIZE + PAGE_SIZE @@ @@ - PAGE_CACHE_MASK + PAGE_MASK @@ expression E; @@ - PAGE_CACHE_ALIGN(E) + PAGE_ALIGN(E) @@ expression E; @@ - page_cache_get(E) + get_page(E) @@ expression E; @@ - page_cache_release(E) + put_page(E) Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-01 14:29:47 +02:00
put_page(page);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
ret = -EEXIST;
goto fail;
case ZSWAP_SWAPCACHE_NEW: /* page is locked */
/* decompress */
dlen = PAGE_SIZE;
src = (u8 *)zpool_map_handle(entry->pool->zpool, entry->handle,
ZPOOL_MM_RO) + sizeof(struct zswap_header);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
dst = kmap_atomic(page);
tfm = *get_cpu_ptr(entry->pool->tfm);
ret = crypto_comp_decompress(tfm, src, entry->length,
dst, &dlen);
put_cpu_ptr(entry->pool->tfm);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
kunmap_atomic(dst);
zpool_unmap_handle(entry->pool->zpool, entry->handle);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
BUG_ON(ret);
BUG_ON(dlen != PAGE_SIZE);
/* page is up to date */
SetPageUptodate(page);
}
/* move it to the tail of the inactive list after end_writeback */
SetPageReclaim(page);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
/* start writeback */
__swap_writepage(page, &wbc, end_swap_bio_write);
mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time ago with promise that one day it will be possible to implement page cache with bigger chunks than PAGE_SIZE. This promise never materialized. And unlikely will. We have many places where PAGE_CACHE_SIZE assumed to be equal to PAGE_SIZE. And it's constant source of confusion on whether PAGE_CACHE_* or PAGE_* constant should be used in a particular case, especially on the border between fs and mm. Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much breakage to be doable. Let's stop pretending that pages in page cache are special. They are not. The changes are pretty straight-forward: - <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN}; - page_cache_get() -> get_page(); - page_cache_release() -> put_page(); This patch contains automated changes generated with coccinelle using script below. For some reason, coccinelle doesn't patch header files. I've called spatch for them manually. The only adjustment after coccinelle is revert of changes to PAGE_CAHCE_ALIGN definition: we are going to drop it later. There are few places in the code where coccinelle didn't reach. I'll fix them manually in a separate patch. Comments and documentation also will be addressed with the separate patch. virtual patch @@ expression E; @@ - E << (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ expression E; @@ - E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ @@ - PAGE_CACHE_SHIFT + PAGE_SHIFT @@ @@ - PAGE_CACHE_SIZE + PAGE_SIZE @@ @@ - PAGE_CACHE_MASK + PAGE_MASK @@ expression E; @@ - PAGE_CACHE_ALIGN(E) + PAGE_ALIGN(E) @@ expression E; @@ - page_cache_get(E) + get_page(E) @@ expression E; @@ - page_cache_release(E) + put_page(E) Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-01 14:29:47 +02:00
put_page(page);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
zswap_written_back_pages++;
spin_lock(&tree->lock);
/* drop local reference */
zswap_entry_put(tree, entry);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
/*
* There are two possible situations for entry here:
* (1) refcount is 1(normal case), entry is valid and on the tree
* (2) refcount is 0, entry is freed and not on the tree
* because invalidate happened during writeback
* search the tree and free the entry if find entry
*/
if (entry == zswap_rb_search(&tree->rbroot, offset))
zswap_entry_put(tree, entry);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
spin_unlock(&tree->lock);
goto end;
/*
* if we get here due to ZSWAP_SWAPCACHE_EXIST
* a load may happening concurrently
* it is safe and okay to not free the entry
* if we free the entry in the following put
* it it either okay to return !0
*/
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
fail:
spin_lock(&tree->lock);
zswap_entry_put(tree, entry);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
spin_unlock(&tree->lock);
end:
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
return ret;
}
static int zswap_shrink(void)
{
struct zswap_pool *pool;
int ret;
pool = zswap_pool_last_get();
if (!pool)
return -ENOENT;
ret = zpool_shrink(pool->zpool, 1, NULL);
zswap_pool_put(pool);
return ret;
}
zswap: same-filled pages handling Zswap is a cache which compresses the pages that are being swapped out and stores them into a dynamically allocated RAM-based memory pool. Experiments have shown that around 10-20% of pages stored in zswap are same-filled pages (i.e. contents of the page are all same), but these pages are handled as normal pages by compressing and allocating memory in the pool. This patch adds a check in zswap_frontswap_store() to identify same-filled page before compression of the page. If the page is a same-filled page, set zswap_entry.length to zero, save the same-filled value and skip the compression of the page and alloction of memory in zpool. In zswap_frontswap_load(), check if value of zswap_entry.length is zero corresponding to the page to be loaded. If zswap_entry.length is zero, fill the page with same-filled value. This saves the decompression time during load. On a ARM Quad Core 32-bit device with 1.5GB RAM by launching and relaunching different applications, out of ~64000 pages stored in zswap, ~11000 pages were same-value filled pages (including zero-filled pages) and ~9000 pages were zero-filled pages. An average of 17% of pages(including zero-filled pages) in zswap are same-value filled pages and 14% pages are zero-filled pages. An average of 3% of pages are same-filled non-zero pages. The below table shows the execution time profiling with the patch. Baseline With patch % Improvement ----------------------------------------------------------------- *Zswap Store Time 26.5ms 18ms 32% (of same value pages) *Zswap Load Time (of same value pages) 25.5ms 13ms 49% ----------------------------------------------------------------- On Ubuntu PC with 2GB RAM, while executing kernel build and other test scripts and running multimedia applications, out of 360000 pages stored in zswap 78000(~22%) of pages were found to be same-value filled pages (including zero-filled pages) and 64000(~17%) are zero-filled pages. So an average of %5 of pages are same-filled non-zero pages. The below table shows the execution time profiling with the patch. Baseline With patch % Improvement ----------------------------------------------------------------- *Zswap Store Time 91ms 74ms 19% (of same value pages) *Zswap Load Time 50ms 7.5ms 85% (of same value pages) ----------------------------------------------------------------- *The execution times may vary with test device used. Dan said: : I did test this patch out this week, and I added some instrumentation to : check the performance impact, and tested with a small program to try to : check the best and worst cases. : : When doing a lot of swap where all (or almost all) pages are same-value, I : found this patch does save both time and space, significantly. The exact : improvement in time and space depends on which compressor is being used, : but roughly agrees with the numbers you listed. : : In the worst case situation, where all (or almost all) pages have the : same-value *except* the final long (meaning, zswap will check each long on : the entire page but then still have to pass the page to the compressor), : the same-value check is around 10-15% of the total time spent in : zswap_frontswap_store(). That's a not-insignificant amount of time, but : it's not huge. Considering that most systems will probably be swapping : pages that aren't similar to the worst case (although I don't have any : data to know that), I'd say the improvement is worth the possible : worst-case performance impact. [srividya.dr@samsung.com: add memset_l instead of for loop] Link: http://lkml.kernel.org/r/20171018104832epcms5p1b2232e2236258de3d03d1344dde9fce0@epcms5p1 Signed-off-by: Srividya Desireddy <srividya.dr@samsung.com> Acked-by: Dan Streetman <ddstreet@ieee.org> Cc: Seth Jennings <sjenning@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Dinakar Reddy Pathireddy <dinakar.p@samsung.com> Cc: SHARAN ALLUR <sharan.allur@samsung.com> Cc: RAJIB BASU <rajib.basu@samsung.com> Cc: JUHUN KIM <juhunkim@samsung.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Timofey Titovets <nefelim4ag@gmail.com> Cc: Andi Kleen <ak@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 01:15:59 +01:00
static int zswap_is_page_same_filled(void *ptr, unsigned long *value)
{
unsigned int pos;
unsigned long *page;
page = (unsigned long *)ptr;
for (pos = 1; pos < PAGE_SIZE / sizeof(*page); pos++) {
if (page[pos] != page[0])
return 0;
}
*value = page[0];
return 1;
}
static void zswap_fill_page(void *ptr, unsigned long value)
{
unsigned long *page;
page = (unsigned long *)ptr;
memset_l(page, value, PAGE_SIZE / sizeof(unsigned long));
}
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
/*********************************
* frontswap hooks
**********************************/
/* attempts to compress and store an single page */
static int zswap_frontswap_store(unsigned type, pgoff_t offset,
struct page *page)
{
struct zswap_tree *tree = zswap_trees[type];
struct zswap_entry *entry, *dupentry;
struct crypto_comp *tfm;
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
int ret;
unsigned int hlen, dlen = PAGE_SIZE;
zswap: same-filled pages handling Zswap is a cache which compresses the pages that are being swapped out and stores them into a dynamically allocated RAM-based memory pool. Experiments have shown that around 10-20% of pages stored in zswap are same-filled pages (i.e. contents of the page are all same), but these pages are handled as normal pages by compressing and allocating memory in the pool. This patch adds a check in zswap_frontswap_store() to identify same-filled page before compression of the page. If the page is a same-filled page, set zswap_entry.length to zero, save the same-filled value and skip the compression of the page and alloction of memory in zpool. In zswap_frontswap_load(), check if value of zswap_entry.length is zero corresponding to the page to be loaded. If zswap_entry.length is zero, fill the page with same-filled value. This saves the decompression time during load. On a ARM Quad Core 32-bit device with 1.5GB RAM by launching and relaunching different applications, out of ~64000 pages stored in zswap, ~11000 pages were same-value filled pages (including zero-filled pages) and ~9000 pages were zero-filled pages. An average of 17% of pages(including zero-filled pages) in zswap are same-value filled pages and 14% pages are zero-filled pages. An average of 3% of pages are same-filled non-zero pages. The below table shows the execution time profiling with the patch. Baseline With patch % Improvement ----------------------------------------------------------------- *Zswap Store Time 26.5ms 18ms 32% (of same value pages) *Zswap Load Time (of same value pages) 25.5ms 13ms 49% ----------------------------------------------------------------- On Ubuntu PC with 2GB RAM, while executing kernel build and other test scripts and running multimedia applications, out of 360000 pages stored in zswap 78000(~22%) of pages were found to be same-value filled pages (including zero-filled pages) and 64000(~17%) are zero-filled pages. So an average of %5 of pages are same-filled non-zero pages. The below table shows the execution time profiling with the patch. Baseline With patch % Improvement ----------------------------------------------------------------- *Zswap Store Time 91ms 74ms 19% (of same value pages) *Zswap Load Time 50ms 7.5ms 85% (of same value pages) ----------------------------------------------------------------- *The execution times may vary with test device used. Dan said: : I did test this patch out this week, and I added some instrumentation to : check the performance impact, and tested with a small program to try to : check the best and worst cases. : : When doing a lot of swap where all (or almost all) pages are same-value, I : found this patch does save both time and space, significantly. The exact : improvement in time and space depends on which compressor is being used, : but roughly agrees with the numbers you listed. : : In the worst case situation, where all (or almost all) pages have the : same-value *except* the final long (meaning, zswap will check each long on : the entire page but then still have to pass the page to the compressor), : the same-value check is around 10-15% of the total time spent in : zswap_frontswap_store(). That's a not-insignificant amount of time, but : it's not huge. Considering that most systems will probably be swapping : pages that aren't similar to the worst case (although I don't have any : data to know that), I'd say the improvement is worth the possible : worst-case performance impact. [srividya.dr@samsung.com: add memset_l instead of for loop] Link: http://lkml.kernel.org/r/20171018104832epcms5p1b2232e2236258de3d03d1344dde9fce0@epcms5p1 Signed-off-by: Srividya Desireddy <srividya.dr@samsung.com> Acked-by: Dan Streetman <ddstreet@ieee.org> Cc: Seth Jennings <sjenning@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Dinakar Reddy Pathireddy <dinakar.p@samsung.com> Cc: SHARAN ALLUR <sharan.allur@samsung.com> Cc: RAJIB BASU <rajib.basu@samsung.com> Cc: JUHUN KIM <juhunkim@samsung.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Timofey Titovets <nefelim4ag@gmail.com> Cc: Andi Kleen <ak@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 01:15:59 +01:00
unsigned long handle, value;
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
char *buf;
u8 *src, *dst;
struct zswap_header zhdr = { .swpentry = swp_entry(type, offset) };
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
if (!zswap_enabled || !tree) {
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
ret = -ENODEV;
goto reject;
}
/* reclaim space if needed */
if (zswap_is_full()) {
zswap_pool_limit_hit++;
if (zswap_shrink()) {
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
zswap_reject_reclaim_fail++;
ret = -ENOMEM;
goto reject;
}
}
/* allocate entry */
entry = zswap_entry_cache_alloc(GFP_KERNEL);
if (!entry) {
zswap_reject_kmemcache_fail++;
ret = -ENOMEM;
goto reject;
}
zswap: same-filled pages handling Zswap is a cache which compresses the pages that are being swapped out and stores them into a dynamically allocated RAM-based memory pool. Experiments have shown that around 10-20% of pages stored in zswap are same-filled pages (i.e. contents of the page are all same), but these pages are handled as normal pages by compressing and allocating memory in the pool. This patch adds a check in zswap_frontswap_store() to identify same-filled page before compression of the page. If the page is a same-filled page, set zswap_entry.length to zero, save the same-filled value and skip the compression of the page and alloction of memory in zpool. In zswap_frontswap_load(), check if value of zswap_entry.length is zero corresponding to the page to be loaded. If zswap_entry.length is zero, fill the page with same-filled value. This saves the decompression time during load. On a ARM Quad Core 32-bit device with 1.5GB RAM by launching and relaunching different applications, out of ~64000 pages stored in zswap, ~11000 pages were same-value filled pages (including zero-filled pages) and ~9000 pages were zero-filled pages. An average of 17% of pages(including zero-filled pages) in zswap are same-value filled pages and 14% pages are zero-filled pages. An average of 3% of pages are same-filled non-zero pages. The below table shows the execution time profiling with the patch. Baseline With patch % Improvement ----------------------------------------------------------------- *Zswap Store Time 26.5ms 18ms 32% (of same value pages) *Zswap Load Time (of same value pages) 25.5ms 13ms 49% ----------------------------------------------------------------- On Ubuntu PC with 2GB RAM, while executing kernel build and other test scripts and running multimedia applications, out of 360000 pages stored in zswap 78000(~22%) of pages were found to be same-value filled pages (including zero-filled pages) and 64000(~17%) are zero-filled pages. So an average of %5 of pages are same-filled non-zero pages. The below table shows the execution time profiling with the patch. Baseline With patch % Improvement ----------------------------------------------------------------- *Zswap Store Time 91ms 74ms 19% (of same value pages) *Zswap Load Time 50ms 7.5ms 85% (of same value pages) ----------------------------------------------------------------- *The execution times may vary with test device used. Dan said: : I did test this patch out this week, and I added some instrumentation to : check the performance impact, and tested with a small program to try to : check the best and worst cases. : : When doing a lot of swap where all (or almost all) pages are same-value, I : found this patch does save both time and space, significantly. The exact : improvement in time and space depends on which compressor is being used, : but roughly agrees with the numbers you listed. : : In the worst case situation, where all (or almost all) pages have the : same-value *except* the final long (meaning, zswap will check each long on : the entire page but then still have to pass the page to the compressor), : the same-value check is around 10-15% of the total time spent in : zswap_frontswap_store(). That's a not-insignificant amount of time, but : it's not huge. Considering that most systems will probably be swapping : pages that aren't similar to the worst case (although I don't have any : data to know that), I'd say the improvement is worth the possible : worst-case performance impact. [srividya.dr@samsung.com: add memset_l instead of for loop] Link: http://lkml.kernel.org/r/20171018104832epcms5p1b2232e2236258de3d03d1344dde9fce0@epcms5p1 Signed-off-by: Srividya Desireddy <srividya.dr@samsung.com> Acked-by: Dan Streetman <ddstreet@ieee.org> Cc: Seth Jennings <sjenning@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Dinakar Reddy Pathireddy <dinakar.p@samsung.com> Cc: SHARAN ALLUR <sharan.allur@samsung.com> Cc: RAJIB BASU <rajib.basu@samsung.com> Cc: JUHUN KIM <juhunkim@samsung.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Timofey Titovets <nefelim4ag@gmail.com> Cc: Andi Kleen <ak@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 01:15:59 +01:00
if (zswap_same_filled_pages_enabled) {
src = kmap_atomic(page);
if (zswap_is_page_same_filled(src, &value)) {
kunmap_atomic(src);
entry->offset = offset;
entry->length = 0;
entry->value = value;
atomic_inc(&zswap_same_filled_pages);
goto insert_entry;
}
kunmap_atomic(src);
}
/* if entry is successfully added, it keeps the reference */
entry->pool = zswap_pool_current_get();
if (!entry->pool) {
ret = -EINVAL;
goto freepage;
}
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
/* compress */
dst = get_cpu_var(zswap_dstmem);
tfm = *get_cpu_ptr(entry->pool->tfm);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
src = kmap_atomic(page);
ret = crypto_comp_compress(tfm, src, PAGE_SIZE, dst, &dlen);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
kunmap_atomic(src);
put_cpu_ptr(entry->pool->tfm);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
if (ret) {
ret = -EINVAL;
goto put_dstmem;
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
}
/* store */
hlen = zpool_evictable(entry->pool->zpool) ? sizeof(zhdr) : 0;
ret = zpool_malloc(entry->pool->zpool, hlen + dlen,
mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd __GFP_WAIT has been used to identify atomic context in callers that hold spinlocks or are in interrupts. They are expected to be high priority and have access one of two watermarks lower than "min" which can be referred to as the "atomic reserve". __GFP_HIGH users get access to the first lower watermark and can be called the "high priority reserve". Over time, callers had a requirement to not block when fallback options were available. Some have abused __GFP_WAIT leading to a situation where an optimisitic allocation with a fallback option can access atomic reserves. This patch uses __GFP_ATOMIC to identify callers that are truely atomic, cannot sleep and have no alternative. High priority users continue to use __GFP_HIGH. __GFP_DIRECT_RECLAIM identifies callers that can sleep and are willing to enter direct reclaim. __GFP_KSWAPD_RECLAIM to identify callers that want to wake kswapd for background reclaim. __GFP_WAIT is redefined as a caller that is willing to enter direct reclaim and wake kswapd for background reclaim. This patch then converts a number of sites o __GFP_ATOMIC is used by callers that are high priority and have memory pools for those requests. GFP_ATOMIC uses this flag. o Callers that have a limited mempool to guarantee forward progress clear __GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall into this category where kswapd will still be woken but atomic reserves are not used as there is a one-entry mempool to guarantee progress. o Callers that are checking if they are non-blocking should use the helper gfpflags_allow_blocking() where possible. This is because checking for __GFP_WAIT as was done historically now can trigger false positives. Some exceptions like dm-crypt.c exist where the code intent is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to flag manipulations. o Callers that built their own GFP flags instead of starting with GFP_KERNEL and friends now also need to specify __GFP_KSWAPD_RECLAIM. The first key hazard to watch out for is callers that removed __GFP_WAIT and was depending on access to atomic reserves for inconspicuous reasons. In some cases it may be appropriate for them to use __GFP_HIGH. The second key hazard is callers that assembled their own combination of GFP flags instead of starting with something like GFP_KERNEL. They may now wish to specify __GFP_KSWAPD_RECLAIM. It's almost certainly harmless if it's missed in most cases as other activity will wake kswapd. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-07 01:28:21 +01:00
__GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM,
&handle);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
if (ret == -ENOSPC) {
zswap_reject_compress_poor++;
goto put_dstmem;
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
}
if (ret) {
zswap_reject_alloc_fail++;
goto put_dstmem;
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
}
buf = zpool_map_handle(entry->pool->zpool, handle, ZPOOL_MM_RW);
memcpy(buf, &zhdr, hlen);
memcpy(buf + hlen, dst, dlen);
zpool_unmap_handle(entry->pool->zpool, handle);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
put_cpu_var(zswap_dstmem);
/* populate entry */
entry->offset = offset;
entry->handle = handle;
entry->length = dlen;
zswap: same-filled pages handling Zswap is a cache which compresses the pages that are being swapped out and stores them into a dynamically allocated RAM-based memory pool. Experiments have shown that around 10-20% of pages stored in zswap are same-filled pages (i.e. contents of the page are all same), but these pages are handled as normal pages by compressing and allocating memory in the pool. This patch adds a check in zswap_frontswap_store() to identify same-filled page before compression of the page. If the page is a same-filled page, set zswap_entry.length to zero, save the same-filled value and skip the compression of the page and alloction of memory in zpool. In zswap_frontswap_load(), check if value of zswap_entry.length is zero corresponding to the page to be loaded. If zswap_entry.length is zero, fill the page with same-filled value. This saves the decompression time during load. On a ARM Quad Core 32-bit device with 1.5GB RAM by launching and relaunching different applications, out of ~64000 pages stored in zswap, ~11000 pages were same-value filled pages (including zero-filled pages) and ~9000 pages were zero-filled pages. An average of 17% of pages(including zero-filled pages) in zswap are same-value filled pages and 14% pages are zero-filled pages. An average of 3% of pages are same-filled non-zero pages. The below table shows the execution time profiling with the patch. Baseline With patch % Improvement ----------------------------------------------------------------- *Zswap Store Time 26.5ms 18ms 32% (of same value pages) *Zswap Load Time (of same value pages) 25.5ms 13ms 49% ----------------------------------------------------------------- On Ubuntu PC with 2GB RAM, while executing kernel build and other test scripts and running multimedia applications, out of 360000 pages stored in zswap 78000(~22%) of pages were found to be same-value filled pages (including zero-filled pages) and 64000(~17%) are zero-filled pages. So an average of %5 of pages are same-filled non-zero pages. The below table shows the execution time profiling with the patch. Baseline With patch % Improvement ----------------------------------------------------------------- *Zswap Store Time 91ms 74ms 19% (of same value pages) *Zswap Load Time 50ms 7.5ms 85% (of same value pages) ----------------------------------------------------------------- *The execution times may vary with test device used. Dan said: : I did test this patch out this week, and I added some instrumentation to : check the performance impact, and tested with a small program to try to : check the best and worst cases. : : When doing a lot of swap where all (or almost all) pages are same-value, I : found this patch does save both time and space, significantly. The exact : improvement in time and space depends on which compressor is being used, : but roughly agrees with the numbers you listed. : : In the worst case situation, where all (or almost all) pages have the : same-value *except* the final long (meaning, zswap will check each long on : the entire page but then still have to pass the page to the compressor), : the same-value check is around 10-15% of the total time spent in : zswap_frontswap_store(). That's a not-insignificant amount of time, but : it's not huge. Considering that most systems will probably be swapping : pages that aren't similar to the worst case (although I don't have any : data to know that), I'd say the improvement is worth the possible : worst-case performance impact. [srividya.dr@samsung.com: add memset_l instead of for loop] Link: http://lkml.kernel.org/r/20171018104832epcms5p1b2232e2236258de3d03d1344dde9fce0@epcms5p1 Signed-off-by: Srividya Desireddy <srividya.dr@samsung.com> Acked-by: Dan Streetman <ddstreet@ieee.org> Cc: Seth Jennings <sjenning@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Dinakar Reddy Pathireddy <dinakar.p@samsung.com> Cc: SHARAN ALLUR <sharan.allur@samsung.com> Cc: RAJIB BASU <rajib.basu@samsung.com> Cc: JUHUN KIM <juhunkim@samsung.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Timofey Titovets <nefelim4ag@gmail.com> Cc: Andi Kleen <ak@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 01:15:59 +01:00
insert_entry:
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
/* map */
spin_lock(&tree->lock);
do {
ret = zswap_rb_insert(&tree->rbroot, entry, &dupentry);
if (ret == -EEXIST) {
zswap_duplicate_entry++;
/* remove from rbtree */
zswap_rb_erase(&tree->rbroot, dupentry);
zswap_entry_put(tree, dupentry);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
}
} while (ret == -EEXIST);
spin_unlock(&tree->lock);
/* update stats */
atomic_inc(&zswap_stored_pages);
zswap_update_total_size();
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
return 0;
put_dstmem:
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
put_cpu_var(zswap_dstmem);
zswap_pool_put(entry->pool);
freepage:
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
zswap_entry_cache_free(entry);
reject:
return ret;
}
/*
* returns 0 if the page was successfully decompressed
* return -1 on entry not found or error
*/
static int zswap_frontswap_load(unsigned type, pgoff_t offset,
struct page *page)
{
struct zswap_tree *tree = zswap_trees[type];
struct zswap_entry *entry;
struct crypto_comp *tfm;
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
u8 *src, *dst;
unsigned int dlen;
int ret;
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
/* find */
spin_lock(&tree->lock);
entry = zswap_entry_find_get(&tree->rbroot, offset);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
if (!entry) {
/* entry was written back */
spin_unlock(&tree->lock);
return -1;
}
spin_unlock(&tree->lock);
zswap: same-filled pages handling Zswap is a cache which compresses the pages that are being swapped out and stores them into a dynamically allocated RAM-based memory pool. Experiments have shown that around 10-20% of pages stored in zswap are same-filled pages (i.e. contents of the page are all same), but these pages are handled as normal pages by compressing and allocating memory in the pool. This patch adds a check in zswap_frontswap_store() to identify same-filled page before compression of the page. If the page is a same-filled page, set zswap_entry.length to zero, save the same-filled value and skip the compression of the page and alloction of memory in zpool. In zswap_frontswap_load(), check if value of zswap_entry.length is zero corresponding to the page to be loaded. If zswap_entry.length is zero, fill the page with same-filled value. This saves the decompression time during load. On a ARM Quad Core 32-bit device with 1.5GB RAM by launching and relaunching different applications, out of ~64000 pages stored in zswap, ~11000 pages were same-value filled pages (including zero-filled pages) and ~9000 pages were zero-filled pages. An average of 17% of pages(including zero-filled pages) in zswap are same-value filled pages and 14% pages are zero-filled pages. An average of 3% of pages are same-filled non-zero pages. The below table shows the execution time profiling with the patch. Baseline With patch % Improvement ----------------------------------------------------------------- *Zswap Store Time 26.5ms 18ms 32% (of same value pages) *Zswap Load Time (of same value pages) 25.5ms 13ms 49% ----------------------------------------------------------------- On Ubuntu PC with 2GB RAM, while executing kernel build and other test scripts and running multimedia applications, out of 360000 pages stored in zswap 78000(~22%) of pages were found to be same-value filled pages (including zero-filled pages) and 64000(~17%) are zero-filled pages. So an average of %5 of pages are same-filled non-zero pages. The below table shows the execution time profiling with the patch. Baseline With patch % Improvement ----------------------------------------------------------------- *Zswap Store Time 91ms 74ms 19% (of same value pages) *Zswap Load Time 50ms 7.5ms 85% (of same value pages) ----------------------------------------------------------------- *The execution times may vary with test device used. Dan said: : I did test this patch out this week, and I added some instrumentation to : check the performance impact, and tested with a small program to try to : check the best and worst cases. : : When doing a lot of swap where all (or almost all) pages are same-value, I : found this patch does save both time and space, significantly. The exact : improvement in time and space depends on which compressor is being used, : but roughly agrees with the numbers you listed. : : In the worst case situation, where all (or almost all) pages have the : same-value *except* the final long (meaning, zswap will check each long on : the entire page but then still have to pass the page to the compressor), : the same-value check is around 10-15% of the total time spent in : zswap_frontswap_store(). That's a not-insignificant amount of time, but : it's not huge. Considering that most systems will probably be swapping : pages that aren't similar to the worst case (although I don't have any : data to know that), I'd say the improvement is worth the possible : worst-case performance impact. [srividya.dr@samsung.com: add memset_l instead of for loop] Link: http://lkml.kernel.org/r/20171018104832epcms5p1b2232e2236258de3d03d1344dde9fce0@epcms5p1 Signed-off-by: Srividya Desireddy <srividya.dr@samsung.com> Acked-by: Dan Streetman <ddstreet@ieee.org> Cc: Seth Jennings <sjenning@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Dinakar Reddy Pathireddy <dinakar.p@samsung.com> Cc: SHARAN ALLUR <sharan.allur@samsung.com> Cc: RAJIB BASU <rajib.basu@samsung.com> Cc: JUHUN KIM <juhunkim@samsung.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Timofey Titovets <nefelim4ag@gmail.com> Cc: Andi Kleen <ak@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 01:15:59 +01:00
if (!entry->length) {
dst = kmap_atomic(page);
zswap_fill_page(dst, entry->value);
kunmap_atomic(dst);
goto freeentry;
}
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
/* decompress */
dlen = PAGE_SIZE;
src = zpool_map_handle(entry->pool->zpool, entry->handle, ZPOOL_MM_RO);
if (zpool_evictable(entry->pool->zpool))
src += sizeof(struct zswap_header);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
dst = kmap_atomic(page);
tfm = *get_cpu_ptr(entry->pool->tfm);
ret = crypto_comp_decompress(tfm, src, entry->length, dst, &dlen);
put_cpu_ptr(entry->pool->tfm);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
kunmap_atomic(dst);
zpool_unmap_handle(entry->pool->zpool, entry->handle);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
BUG_ON(ret);
zswap: same-filled pages handling Zswap is a cache which compresses the pages that are being swapped out and stores them into a dynamically allocated RAM-based memory pool. Experiments have shown that around 10-20% of pages stored in zswap are same-filled pages (i.e. contents of the page are all same), but these pages are handled as normal pages by compressing and allocating memory in the pool. This patch adds a check in zswap_frontswap_store() to identify same-filled page before compression of the page. If the page is a same-filled page, set zswap_entry.length to zero, save the same-filled value and skip the compression of the page and alloction of memory in zpool. In zswap_frontswap_load(), check if value of zswap_entry.length is zero corresponding to the page to be loaded. If zswap_entry.length is zero, fill the page with same-filled value. This saves the decompression time during load. On a ARM Quad Core 32-bit device with 1.5GB RAM by launching and relaunching different applications, out of ~64000 pages stored in zswap, ~11000 pages were same-value filled pages (including zero-filled pages) and ~9000 pages were zero-filled pages. An average of 17% of pages(including zero-filled pages) in zswap are same-value filled pages and 14% pages are zero-filled pages. An average of 3% of pages are same-filled non-zero pages. The below table shows the execution time profiling with the patch. Baseline With patch % Improvement ----------------------------------------------------------------- *Zswap Store Time 26.5ms 18ms 32% (of same value pages) *Zswap Load Time (of same value pages) 25.5ms 13ms 49% ----------------------------------------------------------------- On Ubuntu PC with 2GB RAM, while executing kernel build and other test scripts and running multimedia applications, out of 360000 pages stored in zswap 78000(~22%) of pages were found to be same-value filled pages (including zero-filled pages) and 64000(~17%) are zero-filled pages. So an average of %5 of pages are same-filled non-zero pages. The below table shows the execution time profiling with the patch. Baseline With patch % Improvement ----------------------------------------------------------------- *Zswap Store Time 91ms 74ms 19% (of same value pages) *Zswap Load Time 50ms 7.5ms 85% (of same value pages) ----------------------------------------------------------------- *The execution times may vary with test device used. Dan said: : I did test this patch out this week, and I added some instrumentation to : check the performance impact, and tested with a small program to try to : check the best and worst cases. : : When doing a lot of swap where all (or almost all) pages are same-value, I : found this patch does save both time and space, significantly. The exact : improvement in time and space depends on which compressor is being used, : but roughly agrees with the numbers you listed. : : In the worst case situation, where all (or almost all) pages have the : same-value *except* the final long (meaning, zswap will check each long on : the entire page but then still have to pass the page to the compressor), : the same-value check is around 10-15% of the total time spent in : zswap_frontswap_store(). That's a not-insignificant amount of time, but : it's not huge. Considering that most systems will probably be swapping : pages that aren't similar to the worst case (although I don't have any : data to know that), I'd say the improvement is worth the possible : worst-case performance impact. [srividya.dr@samsung.com: add memset_l instead of for loop] Link: http://lkml.kernel.org/r/20171018104832epcms5p1b2232e2236258de3d03d1344dde9fce0@epcms5p1 Signed-off-by: Srividya Desireddy <srividya.dr@samsung.com> Acked-by: Dan Streetman <ddstreet@ieee.org> Cc: Seth Jennings <sjenning@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Dinakar Reddy Pathireddy <dinakar.p@samsung.com> Cc: SHARAN ALLUR <sharan.allur@samsung.com> Cc: RAJIB BASU <rajib.basu@samsung.com> Cc: JUHUN KIM <juhunkim@samsung.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Timofey Titovets <nefelim4ag@gmail.com> Cc: Andi Kleen <ak@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 01:15:59 +01:00
freeentry:
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
spin_lock(&tree->lock);
zswap_entry_put(tree, entry);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
spin_unlock(&tree->lock);
return 0;
}
/* frees an entry in zswap */
static void zswap_frontswap_invalidate_page(unsigned type, pgoff_t offset)
{
struct zswap_tree *tree = zswap_trees[type];
struct zswap_entry *entry;
/* find */
spin_lock(&tree->lock);
entry = zswap_rb_search(&tree->rbroot, offset);
if (!entry) {
/* entry was written back */
spin_unlock(&tree->lock);
return;
}
/* remove from rbtree */
zswap_rb_erase(&tree->rbroot, entry);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
/* drop the initial reference from entry creation */
zswap_entry_put(tree, entry);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
spin_unlock(&tree->lock);
}
/* frees all zswap entries for the given swap type */
static void zswap_frontswap_invalidate_area(unsigned type)
{
struct zswap_tree *tree = zswap_trees[type];
struct zswap_entry *entry, *n;
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
if (!tree)
return;
/* walk the tree and free everything */
spin_lock(&tree->lock);
rbtree_postorder_for_each_entry_safe(entry, n, &tree->rbroot, rbnode)
zswap_free_entry(entry);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
tree->rbroot = RB_ROOT;
spin_unlock(&tree->lock);
mm/zswap: bugfix: memory leak when re-swapon zswap_tree is not freed when swapoff, and it got re-kmalloced in swapon, so a memory leak occurs. Free the memory of zswap_tree in zswap_frontswap_invalidate_area(). Signed-off-by: Weijie Yang <weijie.yang@samsung.com> Reviewed-by: Bob Liu <bob.liu@oracle.com> Cc: Minchan Kim <minchan@kernel.org> Reviewed-by: Minchan Kim <minchan@kernel.org> Cc: <stable@vger.kernel.org> From: Weijie Yang <weijie.yang@samsung.com> Subject: mm/zswap: bugfix: memory leak when invalidate and reclaim occur concurrently Consider the following scenario: thread 0: reclaim entry x (get refcount, but not call zswap_get_swap_cache_page) thread 1: call zswap_frontswap_invalidate_page to invalidate entry x. finished, entry x and its zbud is not freed as its refcount != 0 now, the swap_map[x] = 0 thread 0: now call zswap_get_swap_cache_page swapcache_prepare return -ENOENT because entry x is not used any more zswap_get_swap_cache_page return ZSWAP_SWAPCACHE_NOMEM zswap_writeback_entry do nothing except put refcount Now, the memory of zswap_entry x and its zpage leak. Modify: - check the refcount in fail path, free memory if it is not referenced. - use ZSWAP_SWAPCACHE_FAIL instead of ZSWAP_SWAPCACHE_NOMEM as the fail path can be not only caused by nomem but also by invalidate. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Weijie Yang <weijie.yang@samsung.com> Reviewed-by: Bob Liu <bob.liu@oracle.com> Cc: Minchan Kim <minchan@kernel.org> Cc: <stable@vger.kernel.org> Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-10-16 22:46:54 +02:00
kfree(tree);
zswap_trees[type] = NULL;
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
}
static void zswap_frontswap_init(unsigned type)
{
struct zswap_tree *tree;
tree = kzalloc(sizeof(*tree), GFP_KERNEL);
if (!tree) {
pr_err("alloc failed, zswap disabled for swap type %d\n", type);
return;
}
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
tree->rbroot = RB_ROOT;
spin_lock_init(&tree->lock);
zswap_trees[type] = tree;
}
static struct frontswap_ops zswap_frontswap_ops = {
.store = zswap_frontswap_store,
.load = zswap_frontswap_load,
.invalidate_page = zswap_frontswap_invalidate_page,
.invalidate_area = zswap_frontswap_invalidate_area,
.init = zswap_frontswap_init
};
/*********************************
* debugfs functions
**********************************/
#ifdef CONFIG_DEBUG_FS
#include <linux/debugfs.h>
static struct dentry *zswap_debugfs_root;
static int __init zswap_debugfs_init(void)
{
if (!debugfs_initialized())
return -ENODEV;
zswap_debugfs_root = debugfs_create_dir("zswap", NULL);
if (!zswap_debugfs_root)
return -ENOMEM;
debugfs_create_u64("pool_limit_hit", S_IRUGO,
zswap_debugfs_root, &zswap_pool_limit_hit);
debugfs_create_u64("reject_reclaim_fail", S_IRUGO,
zswap_debugfs_root, &zswap_reject_reclaim_fail);
debugfs_create_u64("reject_alloc_fail", S_IRUGO,
zswap_debugfs_root, &zswap_reject_alloc_fail);
debugfs_create_u64("reject_kmemcache_fail", S_IRUGO,
zswap_debugfs_root, &zswap_reject_kmemcache_fail);
debugfs_create_u64("reject_compress_poor", S_IRUGO,
zswap_debugfs_root, &zswap_reject_compress_poor);
debugfs_create_u64("written_back_pages", S_IRUGO,
zswap_debugfs_root, &zswap_written_back_pages);
debugfs_create_u64("duplicate_entry", S_IRUGO,
zswap_debugfs_root, &zswap_duplicate_entry);
debugfs_create_u64("pool_total_size", S_IRUGO,
zswap_debugfs_root, &zswap_pool_total_size);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
debugfs_create_atomic_t("stored_pages", S_IRUGO,
zswap_debugfs_root, &zswap_stored_pages);
zswap: same-filled pages handling Zswap is a cache which compresses the pages that are being swapped out and stores them into a dynamically allocated RAM-based memory pool. Experiments have shown that around 10-20% of pages stored in zswap are same-filled pages (i.e. contents of the page are all same), but these pages are handled as normal pages by compressing and allocating memory in the pool. This patch adds a check in zswap_frontswap_store() to identify same-filled page before compression of the page. If the page is a same-filled page, set zswap_entry.length to zero, save the same-filled value and skip the compression of the page and alloction of memory in zpool. In zswap_frontswap_load(), check if value of zswap_entry.length is zero corresponding to the page to be loaded. If zswap_entry.length is zero, fill the page with same-filled value. This saves the decompression time during load. On a ARM Quad Core 32-bit device with 1.5GB RAM by launching and relaunching different applications, out of ~64000 pages stored in zswap, ~11000 pages were same-value filled pages (including zero-filled pages) and ~9000 pages were zero-filled pages. An average of 17% of pages(including zero-filled pages) in zswap are same-value filled pages and 14% pages are zero-filled pages. An average of 3% of pages are same-filled non-zero pages. The below table shows the execution time profiling with the patch. Baseline With patch % Improvement ----------------------------------------------------------------- *Zswap Store Time 26.5ms 18ms 32% (of same value pages) *Zswap Load Time (of same value pages) 25.5ms 13ms 49% ----------------------------------------------------------------- On Ubuntu PC with 2GB RAM, while executing kernel build and other test scripts and running multimedia applications, out of 360000 pages stored in zswap 78000(~22%) of pages were found to be same-value filled pages (including zero-filled pages) and 64000(~17%) are zero-filled pages. So an average of %5 of pages are same-filled non-zero pages. The below table shows the execution time profiling with the patch. Baseline With patch % Improvement ----------------------------------------------------------------- *Zswap Store Time 91ms 74ms 19% (of same value pages) *Zswap Load Time 50ms 7.5ms 85% (of same value pages) ----------------------------------------------------------------- *The execution times may vary with test device used. Dan said: : I did test this patch out this week, and I added some instrumentation to : check the performance impact, and tested with a small program to try to : check the best and worst cases. : : When doing a lot of swap where all (or almost all) pages are same-value, I : found this patch does save both time and space, significantly. The exact : improvement in time and space depends on which compressor is being used, : but roughly agrees with the numbers you listed. : : In the worst case situation, where all (or almost all) pages have the : same-value *except* the final long (meaning, zswap will check each long on : the entire page but then still have to pass the page to the compressor), : the same-value check is around 10-15% of the total time spent in : zswap_frontswap_store(). That's a not-insignificant amount of time, but : it's not huge. Considering that most systems will probably be swapping : pages that aren't similar to the worst case (although I don't have any : data to know that), I'd say the improvement is worth the possible : worst-case performance impact. [srividya.dr@samsung.com: add memset_l instead of for loop] Link: http://lkml.kernel.org/r/20171018104832epcms5p1b2232e2236258de3d03d1344dde9fce0@epcms5p1 Signed-off-by: Srividya Desireddy <srividya.dr@samsung.com> Acked-by: Dan Streetman <ddstreet@ieee.org> Cc: Seth Jennings <sjenning@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Dinakar Reddy Pathireddy <dinakar.p@samsung.com> Cc: SHARAN ALLUR <sharan.allur@samsung.com> Cc: RAJIB BASU <rajib.basu@samsung.com> Cc: JUHUN KIM <juhunkim@samsung.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Timofey Titovets <nefelim4ag@gmail.com> Cc: Andi Kleen <ak@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-01 01:15:59 +01:00
debugfs_create_atomic_t("same_filled_pages", 0444,
zswap_debugfs_root, &zswap_same_filled_pages);
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
return 0;
}
static void __exit zswap_debugfs_exit(void)
{
debugfs_remove_recursive(zswap_debugfs_root);
}
#else
static int __init zswap_debugfs_init(void)
{
return 0;
}
static void __exit zswap_debugfs_exit(void) { }
#endif
/*********************************
* module init and exit
**********************************/
static int __init init_zswap(void)
{
struct zswap_pool *pool;
int ret;
zswap_init_started = true;
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
if (zswap_entry_cache_create()) {
pr_err("entry cache creation failed\n");
goto cache_fail;
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
}
ret = cpuhp_setup_state(CPUHP_MM_ZSWP_MEM_PREPARE, "mm/zswap:prepare",
zswap_dstmem_prepare, zswap_dstmem_dead);
if (ret) {
pr_err("dstmem alloc failed\n");
goto dstmem_fail;
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
}
ret = cpuhp_setup_state_multi(CPUHP_MM_ZSWP_POOL_PREPARE,
"mm/zswap_pool:prepare",
zswap_cpu_comp_prepare,
zswap_cpu_comp_dead);
if (ret)
goto hp_fail;
pool = __zswap_pool_create_fallback();
if (pool) {
pr_info("loaded using pool %s/%s\n", pool->tfm_name,
zpool_get_type(pool->zpool));
list_add(&pool->list, &zswap_pools);
zswap_has_pool = true;
} else {
pr_err("pool creation failed\n");
zswap_enabled = false;
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
}
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
frontswap_register_ops(&zswap_frontswap_ops);
if (zswap_debugfs_init())
pr_warn("debugfs initialization failed\n");
return 0;
hp_fail:
cpuhp_remove_state(CPUHP_MM_ZSWP_MEM_PREPARE);
dstmem_fail:
zswap_entry_cache_destroy();
cache_fail:
zswap: disable changing params if init fails Add zswap_init_failed bool that prevents changing any of the module params, if init_zswap() fails, and set zswap_enabled to false. Change 'enabled' param to a callback, and check zswap_init_failed before allowing any change to 'enabled', 'zpool', or 'compressor' params. Any driver that is built-in to the kernel will not be unloaded if its init function returns error, and its module params remain accessible for users to change via sysfs. Since zswap uses param callbacks, which assume that zswap has been initialized, changing the zswap params after a failed initialization will result in WARNING due to the param callbacks expecting a pool to already exist. This prevents that by immediately exiting any of the param callbacks if initialization failed. This was reported here: https://marc.info/?l=linux-mm&m=147004228125528&w=4 And fixes this WARNING: [ 429.723476] WARNING: CPU: 0 PID: 5140 at mm/zswap.c:503 __zswap_pool_current+0x56/0x60 The warning is just noise, and not serious. However, when init fails, zswap frees all its percpu dstmem pages and its kmem cache. The kmem cache might be serious, if kmem_cache_alloc(NULL, gfp) has problems; but the percpu dstmem pages are definitely a problem, as they're used as temporary buffer for compressed pages before copying into place in the zpool. If the user does get zswap enabled after an init failure, then zswap will likely Oops on the first page it tries to compress (or worse, start corrupting memory). Fixes: 90b0fc26d5db ("zswap: change zpool/compressor at runtime") Link: http://lkml.kernel.org/r/20170124200259.16191-2-ddstreet@ieee.org Signed-off-by: Dan Streetman <dan.streetman@canonical.com> Reported-by: Marcin Miroslaw <marcin@mejor.pl> Cc: Seth Jennings <sjenning@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-03 22:13:09 +01:00
/* if built-in, we aren't unloaded on failure; don't allow use */
zswap_init_failed = true;
zswap_enabled = false;
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
return -ENOMEM;
}
/* must be late so crypto has time to come up */
late_initcall(init_zswap);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Seth Jennings <sjennings@variantweb.net>");
zswap: add to mm/ zswap is a thin backend for frontswap that takes pages that are in the process of being swapped out and attempts to compress them and store them in a RAM-based memory pool. This can result in a significant I/O reduction on the swap device and, in the case where decompressing from RAM is faster than reading from the swap device, can also improve workload performance. It also has support for evicting swap pages that are currently compressed in zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a true cache in that, once the cache is full, the oldest pages can be moved out of zswap to the swap device so newer pages can be compressed and stored in zswap. This patch adds the zswap driver to mm/ Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-11 01:05:03 +02:00
MODULE_DESCRIPTION("Compressed cache for swap pages");