From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756177AbZEKQ6h (ORCPT ); Mon, 11 May 2009 12:58:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753458AbZEKQ61 (ORCPT ); Mon, 11 May 2009 12:58:27 -0400 Received: from brick.kernel.dk ([93.163.65.50]:52799 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752711AbZEKQ60 (ORCPT ); Mon, 11 May 2009 12:58:26 -0400 Date: Mon, 11 May 2009 18:58:26 +0200 From: Jens Axboe To: Jeff Moyer Cc: Andrew Morton , linux-kernel@vger.kernel.org, "Rafael J. Wysocki" Subject: Re: 2.6.30-rc deadline scheduler performance regression for iozone over NFS Message-ID: <20090511165826.GG4694@kernel.dk> References: <20090508120119.8c93cfd7.akpm@linux-foundation.org> <20090511081415.GL4694@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 11 2009, Jeff Moyer wrote: > Jens Axboe writes: > > > On Fri, May 08 2009, Andrew Morton wrote: > >> On Thu, 23 Apr 2009 10:01:58 -0400 > >> Jeff Moyer wrote: > >> > >> > Hi, > >> > > >> > I've been working on CFQ improvements for interleaved I/Os between > >> > processes, and noticed a regression in performance when using the > >> > deadline I/O scheduler. The test uses a server configured with a cciss > >> > array and 1Gb/s ethernet. > >> > > >> > The iozone command line was: > >> > iozone -s 2000000 -r 64 -f /mnt/test/testfile -i 1 -w > >> > > >> > The numbers in the nfsd's row represent the number of nfsd "threads". > >> > These numbers (in MB/s) represent the average of 5 runs. > >> > > >> > v2.6.29 > >> > > >> > nfsd's | 1 | 2 | 4 | 8 > >> > --------+---------------+-------+------ > >> > deadline| 43207 | 67436 | 96289 | 107590 > >> > > >> > 2.6.30-rc1 > >> > > >> > nfsd's | 1 | 2 | 4 | 8 > >> > --------+---------------+-------+------ > >> > deadline| 43732 | 68059 | 76659 | 83231 > >> > > >> > 2.6.30-rc3.block-for-linus > >> > > >> > nfsd's | 1 | 2 | 4 | 8 > >> > --------+---------------+-------+------ > >> > deadline| 46102 | 71151 | 83120 | 82330 > >> > > >> > > >> > Notice the drop for 4 and 8 threads. It may be worth noting that the > >> > default number of NFSD threads is 8. > >> > > >> > >> I guess we should ask Rafael to add this to the post-2.6.29 regression > >> list. > > > > I agree. It'd be nice to bisect this one down, I'm guessing some mm > > change has caused this writeout regression. > > It's not writeout, it's a read test. Doh sorry, I even ran these tests as well a few weeks back. So perhaps some read-ahead change, I didn't look into it. FWIW, on a single SATA drive here, it didn't show any difference. -- Jens Axboe