tree 49e3e620ff2974dc78fad8df0b343b07b75be407
parent 3d470fc385defa60d9af610f05db8e7f8b4f2f5e
author Dimitri Sivanich <sivanich@sgi.com> 1320106186 -0700
committer Linus Torvalds <torvalds@linux-foundation.org> 1320107451 -0700

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>