From: Jens Axboe Subject: Re: Performance degradation with FFSB between 2.6.20 and 2.6.21-rc7 Date: Thu, 19 Apr 2007 11:03:47 +0200 Message-ID: <20070419090346.GE20928@kernel.dk> References: <462622F8.10107@bull.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: ext4 development , Andrew Morton , Linux Kernel Mailing List To: Valerie Clement Return-path: Content-Disposition: inline In-Reply-To: <462622F8.10107@bull.net> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org 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