From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265302AbUETV4z (ORCPT ); Thu, 20 May 2004 17:56:55 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265304AbUETV4z (ORCPT ); Thu, 20 May 2004 17:56:55 -0400 Received: from pao-nav01.pao.digeo.com ([12.47.58.24]:9479 "HELO pao-nav01.pao.digeo.com") by vger.kernel.org with SMTP id S265302AbUETV4o (ORCPT ); Thu, 20 May 2004 17:56:44 -0400 Date: Thu, 20 May 2004 14:59:02 -0700 From: Andrew Morton To: Alexey Kopytov Cc: linuxram@us.ibm.com, nickpiggin@yahoo.com.au, peter@mysql.com, linux-kernel@vger.kernel.org, axboe@suse.de Subject: Re: Random file I/O regressions in 2.6 [patch+results] Message-Id: <20040520145902.27647dee.akpm@osdl.org> In-Reply-To: <200405200506.03006.alexeyk@mysql.com> References: <200405022357.59415.alexeyk@mysql.com> <1084480888.22208.26.camel@dyn319386.beaverton.ibm.com> <1084815010.13559.3.camel@localhost.localdomain> <200405200506.03006.alexeyk@mysql.com> X-Mailer: Sylpheed version 0.9.7 (GTK+ 1.2.10; i586-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 20 May 2004 21:56:22.0514 (UTC) FILETIME=[4A063520:01C43EB5] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org (Resend due to osdl<->vger smtp bunfight) Alexey Kopytov wrote: > > Ram Pai wrote: > > >Attached the cleaned up patch and the performance results of the patch. > > > >Overall Observation: > > 1.Small improvement with iozone with the patch, and overall > > much better performance than 2.4 > > 2.Small/neglegible improvement with DSS workload. > > 3.Negligible impact with sysbench, but results worser than > > 2.4 kernels > > Ram, can you clarify the status of this patch please? Everything we have is now in Linus's tree. And in 2.6.6-mm4. > I ran the same sysbench test on my hardware with patched 2.6.6 and got > 122.2348s execution time, i.e. almost the same results as in the original > tests. Is this patch an intermediate step to improve the sysbench workload on > 2.6, or it just addresses another problem? The patches in Linus's tree improve sysbench significantly here. It's a 256MB 2-way with IDE disks, writeback caching enabled: sysbench --num-threads=16 --test=fileio --file-total-size=2G --file-test-mode=rndrw run 2.4.27-pre2, ext2: Time spent for test: 61.0240s 0.06s user 6.03s system 4% cpu 2:05.95 total Time spent for test: 60.8456s 0.11s user 5.49s system 4% cpu 2:04.94 total 2.6.6, CFQ, ext2: Time spent for test: 85.6614s 0.05s user 5.66s system 3% cpu 2:26.75 total Time spent for test: 85.2090s 0.06s user 5.32s system 3% cpu 2:24.75 total 2.6.6-bk, CFQ, ext2: Time spent for test: 66.7717s 0.04s user 5.54s system 4% cpu 2:06.19 total Time spent for test: 67.5666s 0.04s user 5.10s system 4% cpu 2:06.72 total 2.6.6, as, ext2: Time spent for test: 83.8358s 0.07s user 5.89s system 4% cpu 2:22.92 total Time spent for test: 83.8068s 0.06s user 5.34s system 3% cpu 2:21.33 total 2.6.6-bk, AS, ext2: Time spent for test: 62.5316s 0.05s user 5.27s system 4% cpu 2:01.28 total Time spent for test: 62.7401s 0.04s user 5.17s system 4% cpu 2:00.50 total 2.6.6, deadline, ext2: Time spent for test: 103.0084s 0.06s user 5.76s system 3% cpu 2:40.74 total Time spent for test: 101.9648s 0.07s user 5.35s system 3% cpu 2:38.83 total 2.6.6-bk, deadline, ext2: Time spent for test: 63.3405s 0.03s user 5.49s system 4% cpu 2:01.05 total Time spent for test: 63.5288s 0.03s user 5.05s system 4% cpu 2:00.78 total There's still something wrong here. 2.6.6-bk+deadline is pretty equivalent to 2.4 from an IO scheduler point of view in this test. Yet it's a couple of percent slower. I don't know why you're still seeing significant discrepancies. What sort of disk+controller system are you using? If scsi, what is the tag queue depth set to? Is writeback caching enabled on the disk?