This is a note to let you know that I've just added the patch titled
mm/vmstat.c: cache align vm_stat
to the 3.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-vmstat.c-cache-align-vm_stat.patch
and it can be found in the queue-3.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From a1cb2c60ddc98ff4e5246f410558805401ceee67 Mon Sep 17 00:00:00 2001
From: Dimitri Sivanich <[email protected]>
Date: Mon, 31 Oct 2011 17:09:46 -0700
Subject: mm/vmstat.c: cache align vm_stat
From: Dimitri Sivanich <[email protected]>
commit a1cb2c60ddc98ff4e5246f410558805401ceee67 upstream.
Stable note: Not tracked on Bugzilla. This patch is known to make a big
difference to tmpfs performance on larger machines.
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 <[email protected]>
Acked-by: Christoph Lameter <[email protected]>
Acked-by: Mel Gorman <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Mel Gorman <[email protected]>
---
mm/vmstat.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- 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
Patches currently in stable-queue which might be from [email protected] are
queue-3.0/mm-vmstat.c-cache-align-vm_stat.patch
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