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| author | Dimitri Sivanich <sivanich@sgi.com> | 2011-11-01 01:09:46 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-11-01 01:30:51 +0100 |
| commit | a1cb2c60ddc98ff4e5246f410558805401ceee67 (patch) | |
| tree | 49e3e620ff2974dc78fad8df0b343b07b75be407 | |
| parent | mm: munlock use mapcount to avoid terrible overhead (diff) | |
| download | linux-a1cb2c60ddc98ff4e5246f410558805401ceee67.tar.xz linux-a1cb2c60ddc98ff4e5246f410558805401ceee67.zip | |
mm/vmstat.c: cache align vm_stat
Avoid false sharing of the vm_stat array.
This was found to adversely affect tmpfs I/O performance.
Tests run on a 640 cpu UV system.
With 120 threads doing parallel writes, each to different tmpfs mounts:
No patch: ~300 MB/sec
With vm_stat alignment: ~430 MB/sec
Signed-off-by: Dimitri Sivanich <sivanich@sgi.com>
Acked-by: Christoph Lameter <cl@gentwo.org>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/vmstat.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/vmstat.c b/mm/vmstat.c index 56e529a40517..8fd603b1665e 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -78,7 +78,7 @@ void vm_events_fold_cpu(int cpu) * * vm_stat contains the global counters */ -atomic_long_t vm_stat[NR_VM_ZONE_STAT_ITEMS]; +atomic_long_t vm_stat[NR_VM_ZONE_STAT_ITEMS] __cacheline_aligned_in_smp; EXPORT_SYMBOL(vm_stat); #ifdef CONFIG_SMP |