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Hugh Dickins e504f3fdd6 tmpfs radix_tree: locate_item to speed up swapoff 
We have already acknowledged that swapoff of a tmpfs file is slower than
it was before conversion to the generic radix_tree: a little slower
there will be acceptable, if the hotter paths are faster.

But it was a shock to find swapoff of a 500MB file 20 times slower on my
laptop, taking 10 minutes; and at that rate it significantly slows down
my testing.

Now, most of that turned out to be overhead from PROVE_LOCKING and
PROVE_RCU: without those it was only 4 times slower than before; and
more realistic tests on other machines don't fare as badly.

I've tried a number of things to improve it, including tagging the swap
entries, then doing lookup by tag: I'd expected that to halve the time,
but in practice it's erratic, and often counter-productive.

The only change I've so far found to make a consistent improvement, is
to short-circuit the way we go back and forth, gang lookup packing
entries into the array supplied, then shmem scanning that array for the
target entry.  Scanning in place doubles the speed, so it's now only
twice as slow as before (or three times slower when the PROVEs are on).

So, add radix_tree_locate_item() as an expedient, once-off,
single-caller hack to do the lookup directly in place.  #ifdef it on
CONFIG_SHMEM and CONFIG_SWAP, as much to document its limited
applicability as save space in other configurations.  And, sadly,
#include sched.h for cond_resched().

Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 		2011-08-03 14:25:24 -10:00
..
Kconfig mm Kconfig typo: cleancacne -> cleancache 2011-06-10 14:47:52 +02:00
Kconfig.debug mm: debug-pagealloc: fix kconfig dependency warning 2011-03-22 17:44:02 -07:00
Makefile mm: cleancache core ops functions and config 2011-05-26 10:01:36 -06:00
backing-dev.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/writeback 2011-07-26 10:39:54 -07:00
bootmem.c crash_dump: export is_kdump_kernel to modules, consolidate elfcorehdr_addr, setup_elfcorehdr and saved_max_pfn 2011-03-23 19:47:19 -07:00
bounce.c bounce: call flush_dcache_page() after bounce_copy_vec() 2010-09-09 18:57:25 -07:00
cleancache.c mm: cleancache core ops functions and config 2011-05-26 10:01:36 -06:00
compaction.c mm: compaction: abort compaction if too many pages are isolated and caller is asynchronous V2 2011-06-15 20:04:02 -07:00
debug-pagealloc.c generic debug pagealloc 2009-04-01 08:59:13 -07:00
dmapool.c devres: fix possible use after free 2011-07-25 20:57:14 -07:00
fadvise.c readahead: introduce FMODE_RANDOM for POSIX_FADV_RANDOM 2010-03-06 11:26:25 -08:00
failslab.c fault-injection: add ability to export fault_attr in arbitrary directory 2011-08-03 14:25:20 -10:00
filemap.c mm: a few small updates for radix-swap 2011-08-03 14:25:24 -10:00
filemap_xip.c mm: Convert i_mmap_lock to a mutex 2011-05-25 08:39:18 -07:00
fremap.c mm: don't access vm_flags as 'int' 2011-05-26 09:20:31 -07:00
highmem.c mm,x86: fix kmap_atomic_push vs ioremap_32.c 2010-10-27 18:03:05 -07:00
huge_memory.c mm/huge_memory.c: minor lock simplification in __khugepaged_exit 2011-07-25 20:57:09 -07:00
hugetlb.c mm: hugetlb: fix coding style issues 2011-07-25 20:57:09 -07:00
hwpoison-inject.c Fix common misspellings 2011-03-31 11:26:23 -03:00
init-mm.c atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
internal.h mm: nommu: sort mm->mmap list properly 2011-05-25 08:39:05 -07:00
kmemcheck.c kmemcheck: Fix build errors due to missing slab.h 2010-03-30 22:02:32 +09:00
kmemleak-test.c kmemleak: remove memset by using kzalloc 2011-01-27 18:31:51 +00:00
kmemleak.c atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
ksm.c ksm: fix NULL pointer dereference in scan_get_next_rmap_item() 2011-06-15 20:04:02 -07:00
maccess.c maccess,probe_kernel: Make write/read src const void * 2011-05-25 19:56:23 -04:00
madvise.c fs: kill i_alloc_sem 2011-07-20 20:47:46 -04:00
memblock.c mm/memblock.c: avoid abuse of RED_INACTIVE 2011-07-25 20:57:09 -07:00
memcontrol.c tmpfs: convert mem_cgroup shmem to radix-swap 2011-08-03 14:25:24 -10:00
memory-failure.c mm/memory-failure.c: fix spinlock vs mutex order 2011-06-27 18:00:13 -07:00
memory.c mm/futex: fix futex writes on archs with SW tracking of dirty & young 2011-07-25 20:57:11 -07:00
memory_hotplug.c mm: extend memory hotplug API to allow memory hotplug in virtual machines 2011-07-25 20:57:08 -07:00
mempolicy.c cpusets: randomize node rotor used in cpuset_mem_spread_node() 2011-07-26 16:49:43 -07:00
mempool.c mm: remove broken 'kzalloc' mempool 2009-09-22 07:17:35 -07:00
migrate.c migrate: don't account swapcache as shmem 2011-06-16 15:01:24 -07:00
mincore.c mm: a few small updates for radix-swap 2011-08-03 14:25:24 -10:00
mlock.c mm: don't access vm_flags as 'int' 2011-05-26 09:20:31 -07:00
mm_init.c mm: mminit_loglevel cannot be __meminitdata anymore 2008-08-20 15:40:30 -07:00
mmap.c mmap: fix and tidy up overcommit page arithmetic 2011-07-25 20:57:09 -07:00
mmu_context.c exit: fix oops in sync_mm_rss 2010-03-24 16:31:21 -07:00
mmu_notifier.c thp: mmu_notifier_test_young 2011-01-13 17:32:46 -08:00
mmzone.c mm: page allocator: adjust the per-cpu counter threshold when memory is low 2011-01-13 17:32:31 -08:00
mprotect.c thp: mprotect: transparent huge page support 2011-01-13 17:32:44 -08:00
mremap.c mm: Convert i_mmap_lock to a mutex 2011-05-25 08:39:18 -07:00
msync.c sanitize vfs_fsync calling conventions 2010-05-21 18:31:21 -04:00
nobootmem.c memblock/nobootmem: remove unneeded code from alloc_bootmem_node_high() 2011-05-25 08:39:31 -07:00
nommu.c mmap: fix and tidy up overcommit page arithmetic 2011-07-25 20:57:09 -07:00
oom_kill.c oom: task->mm == NULL doesn't mean the memory was freed 2011-08-01 15:24:12 -10:00
page-writeback.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/writeback 2011-07-26 10:39:54 -07:00
page_alloc.c fault-injection: add ability to export fault_attr in arbitrary directory 2011-08-03 14:25:20 -10:00
page_cgroup.c mm/page_cgroup.c: simplify code by using SECTION_ALIGN_UP() and SECTION_ALIGN_DOWN() macros 2011-07-25 20:57:09 -07:00
page_io.c block: kill off REQ_UNPLUG 2011-03-10 08:52:27 +01:00
page_isolation.c mm: page_isolation: codeclean fix comment and rm unneeded val init 2010-10-26 16:52:11 -07:00
pagewalk.c pagewalk: fix code comment for THP 2011-07-25 20:57:09 -07:00
percpu-km.c percpu: clear memory allocated with the km allocator 2010-10-02 10:28:42 +03:00
percpu-vm.c mm: remove gfp mask from pcpu_get_vm_areas 2011-01-13 17:32:34 -08:00
percpu.c Merge branch 'for-2.6.40' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu 2011-05-24 11:53:42 -07:00
pgtable-generic.c mm/pgtable-generic.c: fix CONFIG_SWAP=n build 2011-01-26 10:49:58 +10:00
prio_tree.c sanitize <linux/prefetch.h> usage 2011-05-20 12:50:29 -07:00
quicklist.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
readahead.c readahead: readahead page allocations are OK to fail 2011-05-25 08:39:25 -07:00
rmap.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/writeback 2011-07-26 10:39:54 -07:00
shmem.c tmpfs radix_tree: locate_item to speed up swapoff 2011-08-03 14:25:24 -10:00
slab.c slab: use NUMA_NO_NODE 2011-07-31 18:14:21 +03:00
slob.c atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
slub.c Merge branch 'slub/lockless' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6 2011-07-30 08:21:48 -10:00
sparse-vmemmap.c tree-wide: fix comment/printk typos 2010-11-01 15:38:34 -04:00
sparse.c mm: make some struct page's const 2011-07-25 20:57:07 -07:00
swap.c mm: batch activate_page() to reduce lock contention 2011-05-25 08:39:37 -07:00
swap_state.c block: remove per-queue plugging 2011-03-10 08:52:07 +01:00
swapfile.c mm: let swap use exceptional entries 2011-08-03 14:25:22 -10:00
thrash.c mm: swap-token: add a comment for priority aging 2011-07-25 20:57:08 -07:00
truncate.c mm: a few small updates for radix-swap 2011-08-03 14:25:24 -10:00
util.c mm: nommu: sort mm->mmap list properly 2011-05-25 08:39:05 -07:00
vmalloc.c atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
vmscan.c memcg: add memory.vmscan_stat 2011-07-26 16:49:42 -07:00
vmstat.c mm, mem-hotplug: update pcp->stat_threshold when memory hotplug occur 2011-05-25 08:39:09 -07:00