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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
..
lzo
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raid6 Move .gitignore from drivers/md to lib/raid6 2010-08-30 17:35:52 +10:00
reed_solomon
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xz XZ: Fix missing <linux/kernel.h> include 2011-07-24 10:00:08 -07:00
zlib_deflate zlib: slim down zlib_deflate() workspace when possible 2011-03-22 17:44:17 -07:00
zlib_inflate inflate_fast: sout is already a short so ptr arith was off by one. 2010-03-12 15:52:44 -08:00
.gitignore
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Kconfig Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next-2.6 into for-davem 2011-06-08 13:44:21 -04:00
Kconfig.debug Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-07-22 16:45:02 -07:00
Kconfig.kgdb mips,kgdb: kdb low level trap catch and stack trace 2010-05-20 21:04:26 -05:00
Kconfig.kmemcheck
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Makefile Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next-2.6 into for-davem 2011-06-08 13:44:21 -04:00
argv_split.c
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atomic64.c atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
atomic64_test.c atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
audit.c audit: support the "standard" <asm-generic/unistd.h> 2011-05-04 14:41:28 -04:00
average.c lib: Improve EWMA efficiency by using bitshifts 2010-12-06 15:58:43 -05:00
bcd.c
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bch.c lib: add shared BCH ECC library 2011-03-11 14:25:50 +00:00
bitmap.c cpusets: randomize node rotor used in cpuset_mem_spread_node() 2011-07-26 16:49:43 -07:00
bitrev.c
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bsearch.c lib: Add generic binary search function to the kernel. 2011-05-19 16:55:27 +09:30
btree.c Fix common misspellings 2011-03-31 11:26:23 -03:00
bug.c modules: Fix module_bug_list list corruption race 2010-10-05 11:29:27 -07:00
bust_spinlocks.c
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check_signature.c
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checksum.c lib/checksum.c: optimize do_csum a bit 2011-07-07 04:52:24 -07:00
cmdline.c
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cordic.c lib: cordic: add library module providing cordic angle calculation 2011-06-03 15:01:07 -04:00
cpu-notifier-error-inject.c fault-injection: add CPU notifier error injection module 2010-05-27 09:12:48 -07:00
cpu_rmap.c lib: cpu_rmap: CPU affinity reverse-mapping 2011-01-24 14:51:56 -08:00
cpumask.c cpumask: alloc_cpumask_var() use NUMA_NO_NODE 2011-07-26 16:49:44 -07:00
crc-ccitt.c
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crc-itu-t.c
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crc-t10dif.c
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crc7.c
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crc8.c lib: crc8: add new library module providing crc8 algorithm 2011-06-03 15:01:06 -04:00
crc16.c
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crc32.c atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
crc32defs.h
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ctype.c
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debug_locks.c Revert "debug_locks: set oops_in_progress if we will log messages." 2010-11-29 15:18:28 -08:00
debugobjects.c debugobjects: Fix boot crash when kmemleak and debugobjects enabled 2011-06-20 14:38:43 +02:00
dec_and_lock.c atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
decompress.c decompressors: add boot-time XZ support 2011-01-13 08:03:25 -08:00
decompress_bunzip2.c Decompressors: include <linux/slab.h> in <linux/decompress/mm.h> 2011-01-13 08:03:23 -08:00
decompress_inflate.c decompressors: check input size in decompress_inflate.c 2011-01-13 08:03:25 -08:00
decompress_unlzma.c Decompressors: validate match distance in decompress_unlzma.c 2011-01-13 08:03:24 -08:00
decompress_unlzo.c Decompressors: fix callback-to-callback mode in decompress_unlzo.c 2011-01-13 08:03:24 -08:00
decompress_unxz.c Fix common misspellings 2011-03-31 11:26:23 -03:00
devres.c devres: fix possible use after free 2011-07-25 20:57:14 -07:00
div64.c div64_u64(): improve precision on 32bit platforms 2010-10-26 16:52:19 -07:00
dma-debug.c dma-debug: print information about leaked entry 2011-04-07 16:31:19 +02:00
dump_stack.c
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dynamic_debug.c dynamic_debug: add #include <linux/sched.h> 2011-02-03 15:59:58 -08:00
extable.c
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fault-inject.c fault-injection: add ability to export fault_attr in arbitrary directory 2011-08-03 14:25:20 -10:00
find_last_bit.c bitops: add #ifndef for each of find bitops 2011-05-26 17:12:38 -07:00
find_next_bit.c arch: remove CONFIG_GENERIC_FIND_{NEXT_BIT,BIT_LE,LAST_BIT} 2011-05-26 17:12:38 -07:00
flex_array.c flex_array: avoid divisions when accessing elements 2011-05-26 17:12:33 -07:00
gcd.c
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gen_crc32table.c crc32: major optimization 2010-05-25 08:07:06 -07:00
genalloc.c lib/genalloc.c: add support for specifying the physical address 2011-05-25 08:39:54 -07:00
halfmd4.c
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hexdump.c include/linux/printk.h lib/hexdump.c: neatening and add CONFIG_PRINTK guard 2011-01-13 08:03:10 -08:00
hweight.c x86: Add optimized popcnt variants 2010-04-06 15:52:11 -07:00
idr.c ida: simplified functions for id allocation 2011-08-03 14:25:20 -10:00
inflate.c MN10300: Don't try and #include <linux/slab.h> in lib/inflate.c from bootloader 2010-08-12 09:51:35 -07:00
int_sqrt.c
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iomap.c iomap: make IOPORT/PCI mapping functions conditional 2011-07-22 18:46:26 +02:00
iomap_copy.c
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iommu-helper.c iommu: inline iommu_num_pages 2010-08-09 20:45:05 -07:00
ioremap.c ACPI, APEI, Generic Hardware Error Source POLL/IRQ/NMI notification type support 2011-01-12 03:06:19 -05:00
irq_regs.c
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is_single_threaded.c
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kasprintf.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
klist.c
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kobject.c Delay struct net freeing while there's a sysfs instance refering to it 2011-06-12 17:45:41 -04:00
kobject_uevent.c kobject_uevent: fix typo in comments 2010-08-23 18:12:46 -07:00
kref.c kref: Add a kref_sub function 2010-11-22 13:25:13 +10:00
kstrtox.c lib: make _tolower() public 2011-07-25 20:57:16 -07:00
lcm.c lib/lcm.c: quiet sparse noise 2011-07-25 20:57:15 -07:00
libcrc32c.c
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list_debug.c Expand CONFIG_DEBUG_LIST to several other list operations 2011-02-18 11:32:28 -08:00
list_sort.c lib/list_sort: test: check element addresses 2010-10-26 16:52:19 -07:00
locking-selftest-hardirq.h
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locking-selftest-mutex.h
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locking-selftest-rlock-hardirq.h
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locking-selftest-rlock-softirq.h
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locking-selftest-rlock.h
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locking-selftest-rsem.h
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locking-selftest-softirq.h
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locking-selftest-spin-hardirq.h
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locking-selftest-spin-softirq.h
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locking-selftest-spin.h
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locking-selftest-wlock-hardirq.h
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locking-selftest-wlock-softirq.h
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locking-selftest-wlock.h
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locking-selftest-wsem.h
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locking-selftest.c rcu: Fix unpaired rcu_irq_enter() from locking selftests 2011-05-26 09:42:19 -07:00
lru_cache.c lru_cache: use correct type in sizeof for allocation 2011-05-25 08:39:52 -07:00
nlattr.c net: fix nla_policy_len to actually _iterate_ over the policy 2011-02-28 12:38:25 -08:00
parser.c Fix common misspellings 2011-03-31 11:26:23 -03:00
percpu_counter.c percpucounter: Optimize __percpu_counter_add a bit through the use of this_cpu() options. 2010-12-17 15:07:18 +01:00
plist.c plist: Remove the need to supply locks to plist heads 2011-07-08 14:02:53 +02:00
prio_heap.c
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prio_tree.c
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proportions.c
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radix-tree.c tmpfs radix_tree: locate_item to speed up swapoff 2011-08-03 14:25:24 -10:00
random32.c Merge branch 'master' into for-next 2010-06-16 18:08:13 +02:00
ratelimit.c ratelimit: fix the return value when __ratelimit() fails to acquire the lock 2010-04-07 08:38:04 -07:00
rational.c
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rbtree.c Export the augmented rbtree helper functions 2011-01-28 12:16:59 +10:00
reciprocal_div.c
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rwsem-spinlock.c rwsem generic spinlock: use IRQ save/restore spinlocks 2010-04-07 16:15:05 -07:00
rwsem.c rwsem: Remove redundant asmregparm annotation 2011-01-27 12:30:40 +01:00
scatterlist.c scatterlist: prevent invalid free when alloc fails 2010-08-30 19:55:09 +02:00
sha1.c
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show_mem.c arch, mm: filter disallowed nodes from arch specific show_mem functions 2011-05-25 08:39:03 -07:00
smp_processor_id.c
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sort.c
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spinlock_debug.c
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string.c Add a strtobool function matching semantics of existing in kernel equivalents 2011-05-19 16:55:28 +09:30
string_helpers.c
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swiotlb.c swiotlb: Export swioltb_nr_tbl and utilize it as appropiate. 2011-06-06 15:41:16 -04:00
syscall.c
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test-kstrtox.c kstrtox: fix compile warnings in test 2011-04-14 16:06:54 -07:00
textsearch.c textsearch: doc - fix spelling in lib/textsearch.c. 2011-01-24 23:33:30 -08:00
timerqueue.c Fix common misspellings 2011-03-31 11:26:23 -03:00
ts_bm.c
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ts_fsm.c
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ts_kmp.c
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uuid.c Unified UUID/GUID definition 2010-05-19 22:40:47 -04:00
vsprintf.c Merge 'akpm' patch series 2011-07-25 21:00:19 -07:00