Messages in this thread Patch in this message | | | From | Mel Gorman <> | Subject | [PATCH 01/34] mm: vmstat: cache align vm_stat | Date | Mon, 23 Jul 2012 14:38:14 +0100 |
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From: Dimitri Sivanich <sivanich@sgi.com>
commit a1cb2c60ddc98ff4e5246f410558805401ceee67 upstream.
Stable note: Not tracked on Bugzilla. This patch is known to make a big difference to tmpfs performance on larger machines.
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: Mel Gorman <mgorman@suse.de> --- mm/vmstat.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/vmstat.c b/mm/vmstat.c index 20c18b7..6559013 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 -- 1.7.9.2
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