From: Andrew Morton <akpm@linux-foundation.org>
To: Christoph Lameter <cl@gentwo.org>
Cc: Dimitri Sivanich <sivanich@sgi.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Mel Gorman <mel@csn.ul.ie>
Subject: Re: [PATCH] Reduce vm_stat cacheline contention in __vm_enough_memory
Date: Thu, 13 Oct 2011 13:50:32 -0700 [thread overview]
Message-ID: <20111013135032.7c2c54cd.akpm@linux-foundation.org> (raw)
In-Reply-To: <alpine.DEB.2.00.1110131052300.18473@router.home>
On Thu, 13 Oct 2011 10:54:30 -0500 (CDT)
Christoph Lameter <cl@gentwo.org> wrote:
> On Thu, 13 Oct 2011, Dimitri Sivanich wrote:
>
> > > increase the allowed delta per zone if frequent updates occur via the
> > > overflow checks in vmstat.c. See calculate_*_threshold there.
> >
> > I tried changing the threshold in both directions, with slower throughput in
> > both cases.
>
> If that is the case check for the vm_stat cacheline being shared with
> another hot kernel variable variable. Maybe that causes cacheline
> eviction.
yup. `nm -n vmlinux'.
> If there are no updates occurring for a while (due to increased deltas
> and/or vmstat updates) then the vm_stat cacheline should be able to stay
> in shared mode in multiple processors and the performance should increase.
>
We could cacheline align vm_stat[]. But the thing is pretty small - we
couild put each entry in its own cacheline.
WARNING: multiple messages have this Message-ID (diff)
From: Andrew Morton <akpm@linux-foundation.org>
To: Christoph Lameter <cl@gentwo.org>
Cc: Dimitri Sivanich <sivanich@sgi.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Mel Gorman <mel@csn.ul.ie>
Subject: Re: [PATCH] Reduce vm_stat cacheline contention in __vm_enough_memory
Date: Thu, 13 Oct 2011 13:50:32 -0700 [thread overview]
Message-ID: <20111013135032.7c2c54cd.akpm@linux-foundation.org> (raw)
In-Reply-To: <alpine.DEB.2.00.1110131052300.18473@router.home>
On Thu, 13 Oct 2011 10:54:30 -0500 (CDT)
Christoph Lameter <cl@gentwo.org> wrote:
> On Thu, 13 Oct 2011, Dimitri Sivanich wrote:
>
> > > increase the allowed delta per zone if frequent updates occur via the
> > > overflow checks in vmstat.c. See calculate_*_threshold there.
> >
> > I tried changing the threshold in both directions, with slower throughput in
> > both cases.
>
> If that is the case check for the vm_stat cacheline being shared with
> another hot kernel variable variable. Maybe that causes cacheline
> eviction.
yup. `nm -n vmlinux'.
> If there are no updates occurring for a while (due to increased deltas
> and/or vmstat updates) then the vm_stat cacheline should be able to stay
> in shared mode in multiple processors and the performance should increase.
>
We could cacheline align vm_stat[]. But the thing is pretty small - we
couild put each entry in its own cacheline.
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next prev parent reply other threads:[~2011-10-13 20:50 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-12 16:02 [PATCH] Reduce vm_stat cacheline contention in __vm_enough_memory Dimitri Sivanich
2011-10-12 19:01 ` Andrew Morton
2011-10-12 19:01 ` Andrew Morton
2011-10-12 19:57 ` Christoph Lameter
2011-10-12 19:57 ` Christoph Lameter
2011-10-13 15:06 ` Mel Gorman
2011-10-13 15:06 ` Mel Gorman
2011-10-13 15:59 ` Andi Kleen
2011-10-13 15:59 ` Andi Kleen
2011-10-13 15:23 ` Dimitri Sivanich
2011-10-13 15:23 ` Dimitri Sivanich
2011-10-13 15:54 ` Christoph Lameter
2011-10-13 15:54 ` Christoph Lameter
2011-10-13 20:50 ` Andrew Morton [this message]
2011-10-13 20:50 ` Andrew Morton
2011-10-13 21:02 ` Christoph Lameter
2011-10-13 21:02 ` Christoph Lameter
2011-10-13 21:24 ` Andrew Morton
2011-10-13 21:24 ` Andrew Morton
2011-10-14 12:25 ` Dimitri Sivanich
2011-10-14 12:25 ` Dimitri Sivanich
2011-10-14 13:50 ` Dimitri Sivanich
2011-10-14 13:50 ` Dimitri Sivanich
2011-10-14 13:57 ` Christoph Lameter
2011-10-14 13:57 ` Christoph Lameter
2011-10-14 14:19 ` Dimitri Sivanich
2011-10-14 14:19 ` Dimitri Sivanich
2011-10-14 14:34 ` Christoph Lameter
2011-10-14 14:34 ` Christoph Lameter
2011-10-14 15:18 ` Christoph Lameter
2011-10-14 15:18 ` Christoph Lameter
2011-10-14 16:16 ` Dimitri Sivanich
2011-10-14 16:16 ` Dimitri Sivanich
2011-10-18 13:48 ` Dimitri Sivanich
2011-10-18 13:48 ` Dimitri Sivanich
2011-10-18 14:36 ` Christoph Lameter
2011-10-18 14:36 ` Christoph Lameter
2011-10-18 15:48 ` Andi Kleen
2011-10-18 15:48 ` Andi Kleen
2011-10-19 1:16 ` David Rientjes
2011-10-19 1:16 ` David Rientjes
2011-10-19 14:54 ` Dimitri Sivanich
2011-10-19 14:54 ` Dimitri Sivanich
2011-10-19 15:31 ` Christoph Lameter
2011-10-19 15:31 ` Christoph Lameter
2011-10-24 14:59 ` Dimitri Sivanich
2011-10-24 14:59 ` Dimitri Sivanich
[not found] ` <CADE8fzrdMOBF1RyyEpMVi8aKcgOVKRQSKi0=c1Qvh3p6hHcXRA@mail.gmail.com>
2011-10-13 0:07 ` Tim Chen
2011-10-13 0:07 ` Tim Chen
2011-10-13 14:15 ` Christoph Lameter
2011-10-13 14:15 ` Christoph Lameter
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