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Message-ID: <20080612093121.586f09c6@bree.surriel.com>
Date: Thu, 12 Jun 2008 09:31:21 -0400
From: Rik van Riel <riel@...hat.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org,
Lee Schermerhorn <lee.schermerhorn@...com>,
Kosaki Motohiro <kosaki.motohiro@...fujitsu.com>
Subject: Re: [PATCH -mm 00/24] VM pageout scalability improvements (V12)
On Wed, 11 Jun 2008 22:34:30 -0700
Andrew Morton <akpm@...ux-foundation.org> wrote:
> On a 900MB 2-way, allocate and memset 1000MB.
> Seems to have saved a little CPU but the IO patterns got worse.
In previous tests on my 16GB system, a 16GB fillmem (goes into swap)
saves enough CPU time to make up for potentially worse detection of
the working set (well, not like this program really has a working set).
I'll try this out myself on a smaller system and see if there's
something I can do to make it better.
> qsbench, 4 processes, memory size tuned to threshold-of-swapping*1.1:
>
> Mainline:
>
> vmm:/home/akpm/qsbench> time ./qsbench -p 4 -m 230
> ./qsbench -p 4 -m 230 175.45s user 45.67s system 60% cpu 6:08.40 total
>
> 2.6.26-rc5-mm3:
>
> vmm:/home/akpm/qsbench> time ./qsbench -p 4 -m 230
> ./qsbench -p 4 -m 230 178.21s user 28.49s system 99% cpu 3:27.14 total
>
> So woot! Professional qsbench users will be pleased ;) It could have
> been a fluke though - iirc qsbench is pretty unstable, especially on
> the threshold.
Ignoring references that happen on the active list, only acting
on re-references that happen on the inactive list, gives anonymous
memory something that closer resembles the use-once policy.
Better for some workloads, but potentially worse for others.
Definately worth tweaking the system though, to get performance
as close to where we want it as possible :)
> Main thing is: it seems stable. Old LTP ran for an hour or so before I
> hit the msgctl08 crash (which is a regression in current mainline).
Our main focus has been on stability for the past few months,
trying to get the whole series integrated.
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