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Message-ID: <20070419090346.GE20928@kernel.dk>
Date: Thu, 19 Apr 2007 11:03:47 +0200
From: Jens Axboe <jens.axboe@...cle.com>
To: Valerie Clement <valerie.clement@...l.net>
Cc: ext4 development <linux-ext4@...r.kernel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Performance degradation with FFSB between 2.6.20 and 2.6.21-rc7
On Wed, Apr 18 2007, Valerie Clement wrote:
>
> Running benchmark tests (FFSB) on an ext4 filesystem, I noticed a
> performance degradation (about 15-20 percent) in sequential write tests
> between 2.6.19-rc6 and 2.6.21-rc4 kernels.
>
> I ran the same tests on ext3 and XFS filesystems and I saw the same
> performance difference between the two kernel versions for these two
> filesystems.
>
> I have also reproduced it between 2.6.20.7 and 2.6.21-rc7.
> The FFSB tests run 16 threads, each creating 1GB files. The tests were
> done on the same x86_64 system, with the same kernel configuration and
> on the same scsi device. Below are the throughput values given by FFSB.
>
> kernel XFS ext3
> ----------
> 2.6.20.7 48 MB/sec 44 MB/sec
>
> 2.6.21-rc7 38 MB/sec 37 MB/sec
>
> Did anyone else run across the problem?
> Is there a known issue?
Please tell me how you are running ffsb, and also please include a
dmessg from a booted system.
--
Jens Axboe
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