Subject: Re: XFS filesystem performance drop in kernels 2.6.16+
From: Russell Cattelan <cattelan@thebarn.com>
To: "Igor A. Valcov" <viaprog@gmail.com>
Cc: linux-kernel <linux-kernel@vger.kernel.org>
In-Reply-To: <bde600590611090930g3ab97aq3c76d7bca4ec267f@mail.gmail.com>
References: <bde600590611090930g3ab97aq3c76d7bca4ec267f@mail.gmail.com>
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Date: Thu, 09 Nov 2006 12:08:35 -0600
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On Thu, 2006-11-09 at 20:30 +0300, Igor A. Valcov wrote:
> Hello,
>=20
> For one of our projects we have a test program that measures file
> system performance by writing up to 1000 files simultaneously. After
> installing kernel v2.6.16 we noticed that XFS performance dropped by a
> factor of 5 (tests that took around 4 minutes on kernel 2.6.15 now
> take around 20 minutes to complete). We then checked all kernels
> starting from 2.6.16 up to 2.6.19-rc5 with the same unpleasant result.
> The funny thing about all this is that we chose XFS for that
> particular project specifically because it was about 5 times faster
> with the tests than the other file systems. Now they all take about
> the same time.
>=20
> I also noticed that I/O barriers were introduced in v2.6.16 and
> thought they may be the cause, but mounting the file system with
> 'nobarrier' doesn't seem to affect the performance in any way.
>=20
> Any thoughts on the matter are appreciated.
I would try verifying the problem on a non ide disk just
to confirm the write barrier theory.

Also file a bug.
http://oss/sgi.com/bugzilla
include test case and hard description if possible.


>=20
> Thanks in advance,

--=20
Russell Cattelan <cattelan@thebarn.com>

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