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3a79d52aa3
linux/mm
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Waiman Long 3a79d52aa3 mm, thp: replace smp_mb after atomic_add by smp_mb__after_atomic 
In some architectures like x86, atomic_add() is a full memory barrier.
In that case, an additional smp_mb() is just a waste of time.  This
patch replaces that smp_mb() by smp_mb__after_atomic() which will avoid
the redundant memory barrier in some architectures.

With a 3.16-rc1 based kernel, this patch reduced the execution time of
breaking 1000 transparent huge pages from 38,245us to 30,964us.  A
reduction of 19% which is quite sizeable.  It also reduces the %cpu time
of the __split_huge_page_refcount function in the perf profile from
2.18% to 1.15%.

Signed-off-by: Waiman Long <Waiman.Long@hp.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Scott J Norton <scott.norton@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-08-06 18:01:17 -07:00
..
backing-dev.c arch: Mass conversion of smp_mb__*() 2014-04-18 14:20:48 +02:00
balloon_compaction.c mm: print more details for bad_page() 2014-01-23 16:36:50 -08:00
bootmem.c mm/bootmem.c: remove unused local `map' 2013-11-13 12:09:09 +09:00
cleancache.c mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE 2014-01-23 16:36:50 -08:00
cma.c mm, CMA: clean-up log message 2014-08-06 18:01:16 -07:00
compaction.c mm, compaction: properly signal and act upon lock and need_sched() contention 2014-06-04 16:54:11 -07:00
debug-pagealloc.c
dmapool.c mm/dmapool.c: reuse devres_release() to free resources 2014-06-04 16:54:08 -07:00
early_ioremap.c mm: create generic early_ioremap() support 2014-04-07 16:36:15 -07:00
fadvise.c teach SYSCALL_DEFINE<n> how to deal with long long/unsigned long long 2013-03-03 22:46:22 -05:00
failslab.c
filemap_xip.c seqcount: Add lockdep functionality to seqcount/seqlock structures 2013-11-06 12:40:26 +01:00
filemap.c Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-08-04 16:23:30 -07:00
fremap.c mm: mark remap_file_pages() syscall as deprecated 2014-06-06 16:08:17 -07:00
frontswap.c swap: change swap_list_head to plist, add swap_avail_head 2014-06-04 16:54:07 -07:00
gup.c mm: cleanup __get_user_pages() 2014-06-04 16:54:05 -07:00
highmem.c Some nice cleanups, and even a patch my wife did as a "live" demo for 2012-12-20 08:37:05 -08:00
huge_memory.c mm, thp: replace smp_mb after atomic_add by smp_mb__after_atomic 2014-08-06 18:01:17 -07:00
hugetlb_cgroup.c cgroup: replace cgroup_add_cftypes() with cgroup_add_legacy_cftypes() 2014-07-15 11:05:09 -04:00
hugetlb.c kexec: export free_huge_page to VMCOREINFO 2014-07-30 17:16:13 -07:00
hwpoison-inject.c mm/hwpoison: add '#' to hwpoison_inject 2014-01-21 16:19:48 -08:00
init-mm.c
internal.h mm/internal.h: use nth_page 2014-08-06 18:01:16 -07:00
interval_tree.c mm: add CONFIG_DEBUG_VM_RB build option 2012-10-09 16:22:42 +09:00
iov_iter.c bio_vec-backed iov_iter 2014-05-06 17:39:45 -04:00
Kconfig CMA: generalize CMA reserved area management functionality 2014-08-06 18:01:16 -07:00
Kconfig.debug
kmemcheck.c
kmemleak-test.c mm/kmemleak-test.c: use pr_fmt for logging 2014-06-06 16:08:18 -07:00
kmemleak.c mm: introduce kmemleak_update_trace() 2014-06-06 16:08:17 -07:00
ksm.c sched: Remove proliferation of wait_on_bit() action functions 2014-07-16 15:10:39 +02:00
list_lru.c mm: keep page cache radix tree nodes in check 2014-04-03 16:21:01 -07:00
maccess.c
madvise.c mm: madvise: fix MADV_WILLNEED on shmem swapouts 2014-05-23 09:37:29 -07:00
Makefile CMA: generalize CMA reserved area management functionality 2014-08-06 18:01:16 -07:00
memblock.c mm/memblock.c: call kmemleak directly from memblock_(alloc|free) 2014-06-06 16:08:17 -07:00
memcontrol.c Merge branch 'for-3.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2014-08-04 10:11:28 -07:00
memory_hotplug.c mem-hotplug: introduce MMOP_OFFLINE to replace the hard coding -1 2014-08-06 18:01:16 -07:00
memory-failure.c hwpoison: call action_result() in failure path of hwpoison_user_mappings() 2014-07-30 17:16:13 -07:00
memory.c mm/memory.c: use entry = ACCESS_ONCE(*pte) in handle_pte_fault() 2014-08-06 18:01:15 -07:00
mempolicy.c Merge branch 'for-3.16-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2014-07-10 11:38:23 -07:00
mempool.c mm/mempool.c: update the kmemleak stack trace for mempool allocations 2014-06-06 16:08:17 -07:00
migrate.c mm: fix direct reclaim writeback regression 2014-07-26 14:38:50 -07:00
mincore.c mm + fs: prepare for non-page entries in page cache radix trees 2014-04-03 16:21:00 -07:00
mlock.c mm: try_to_unmap_cluster() should lock_page() before mlocking 2014-04-07 16:35:57 -07:00
mm_init.c mm: bring back /sys/kernel/mm 2014-01-27 21:02:39 -08:00
mmap.c mm: convert some level-less printks to pr_* 2014-06-06 16:08:18 -07:00
mmu_context.c sched/mm: call finish_arch_post_lock_switch in idle_task_exit and use_mm 2014-02-21 08:50:17 +01:00
mmu_notifier.c mm: audit/fix non-modular users of module_init in core code 2014-01-23 16:36:52 -08:00
mmzone.c mm: numa: Change page last {nid,pid} into {cpu,pid} 2013-10-09 14:47:45 +02:00
mprotect.c mm: move mmu notifier call from change_protection to change_pmd_range 2014-04-07 16:35:50 -07:00
mremap.c mm, thp: close race between mremap() and split_huge_page() 2014-05-11 17:55:48 +09:00
msync.c msync: fix incorrect fstart calculation 2014-07-03 09:21:53 -07:00
nobootmem.c mm/memblock.c: call kmemleak directly from memblock_(alloc|free) 2014-06-06 16:08:17 -07:00
nommu.c mm: nommu: per-thread vma cache fix 2014-06-23 16:47:43 -07:00
oom_kill.c mm, oom: base root bonus on current usage 2014-01-30 16:56:56 -08:00
page_alloc.c mm: page_alloc: simplify drain_zone_pages by using min() 2014-08-06 18:01:16 -07:00
page_cgroup.c mm/page_cgroup.c: mark functions as static 2014-04-03 16:21:02 -07:00
page_io.c fix __swap_writepage() compile failure on old gcc versions 2014-06-14 19:30:48 -05:00
page_isolation.c mm: memory-hotplug: enable memory hotplug to handle hugepage 2013-09-11 15:57:48 -07:00
page-writeback.c mm/page-writeback.c: fix divide by zero in bdi_dirty_limits() 2014-07-30 17:16:13 -07:00
pagewalk.c mm/pagewalk.c: fix walk_page_range() access of wrong PTEs 2013-10-30 14:27:03 -07:00
percpu-km.c
percpu-vm.c
percpu.c percpu: Use ALIGN macro instead of hand coding alignment calculation 2014-06-19 11:00:27 -04:00
pgtable-generic.c mm: fix TLB flush race between migration, and change_protection_range 2013-12-18 19:04:51 -08:00
process_vm_access.c start adding the tag to iov_iter 2014-05-06 17:32:49 -04:00
quicklist.c
readahead.c mm/readahead.c: remove unused file_ra_state from count_history_pages 2014-08-06 18:01:15 -07:00
rmap.c mm/rmap.c: fix pgoff calculation to handle hugepage correctly 2014-07-23 15:10:54 -07:00
shmem.c shmem: fix splicing from a hole while it's punched 2014-07-23 15:10:55 -07:00
slab_common.c mm: move slab related stuff from util.c to slab_common.c 2014-08-06 18:01:15 -07:00
slab.c mm/slab.c: fix comments 2014-08-06 18:01:15 -07:00
slab.h slab: convert last use of __FUNCTION__ to __func__ 2014-08-06 18:01:15 -07:00
slob.c slab: get_online_mems for kmem_cache_{create,destroy,shrink} 2014-06-04 16:53:59 -07:00
slub.c slab: fix the alias count (via sysfs) of slab cache 2014-08-06 18:01:15 -07:00
sparse-vmemmap.c mm/sparse: use memblock apis for early memory allocations 2014-01-21 16:19:47 -08:00
sparse.c mm: use macros from compiler.h instead of __attribute__((...)) 2014-04-07 16:35:54 -07:00
swap_state.c mm: page_alloc: convert hot/cold parameter and immediate callers to bool 2014-06-04 16:54:09 -07:00
swap.c mm: non-atomically mark page accessed during page cache allocation where possible 2014-06-04 16:54:10 -07:00
swapfile.c mm/swapfile.c: delete the "last_in_cluster < scan_base" loop in the body of scan_swap_map() 2014-06-04 16:54:12 -07:00
truncate.c mm/fs: fix pessimization in hole-punching pagecache 2014-07-23 15:10:55 -07:00
util.c mm: move slab related stuff from util.c to slab_common.c 2014-08-06 18:01:15 -07:00
vmacache.c mm,vmacache: optimize overflow system-wide flushing 2014-06-04 16:53:57 -07:00
vmalloc.c vmalloc: use rcu list iterator to reduce vmap_area_lock contention 2014-08-06 18:01:15 -07:00
vmpressure.c arm, pm, vmpressure: add missing slab.h includes 2014-02-03 13:24:01 -05:00
vmscan.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
vmstat.c mm: use the light version __mod_zone_page_state in mlocked_vma_newpage() 2014-06-04 16:54:07 -07:00
workingset.c mm: keep page cache radix tree nodes in check 2014-04-03 16:21:01 -07:00
zbud.c mm/zbud.c: make size unsigned like unique callsite 2014-06-04 16:54:13 -07:00
zsmalloc.c zsmalloc: fixup trivial zs size classes value in comments 2014-06-04 16:54:13 -07:00
zswap.c mm/zswap: NUMA aware allocation for zswap_dstmem 2014-06-04 16:54:14 -07:00