From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761072AbXGFLZT (ORCPT ); Fri, 6 Jul 2007 07:25:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755894AbXGFLZI (ORCPT ); Fri, 6 Jul 2007 07:25:08 -0400 Received: from main.gmane.org ([80.91.229.2]:54409 "EHLO ciao.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753783AbXGFLZH (ORCPT ); Fri, 6 Jul 2007 07:25:07 -0400 X-Injected-Via-Gmane: http://gmane.org/ To: linux-kernel@vger.kernel.org From: Brice Figureau Subject: Re: Understanding I/O behaviour Date: Fri, 6 Jul 2007 10:15:52 +0000 (UTC) Message-ID: References: <9a8748490707051653q6e1b6bf3g9a3d6edf213867d9@mail.gmail.com> <684951.37870.qm@web32606.mail.mud.yahoo.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Complaints-To: usenet@sea.gmane.org X-Gmane-NNTP-Posting-Host: main.gmane.org User-Agent: Loom/3.14 (http://gmane.org/) X-Loom-IP: 213.41.185.138 (Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.1.3) Gecko/20070310 Iceweasel/2.0.0.3 (Debian-2.0.0.3-2)) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Martin Knoblauch knobisoft.de> writes: > --- Jesper Juhl gmail.com> wrote: > > > On 06/07/07, Robert Hancock shaw.ca> wrote: > > [snip] > > > > > > Try playing with reducing /proc/sys/vm/dirty_ratio and see how that > > > helps. This workload will fill up memory with dirty data very > > quickly, > > > and it seems like system responsiveness often goes down the toilet > > when > > > this happens and the system is going crazy trying to write it all > > out. > > > > > > > Perhaps trying out a different elevator would also be worthwhile. > > > > AS seems to be the best one (NOOP and DeadLine seem to be equally OK). > CFQ gives less (about 10-15%) throughput except for the kernel with the > cfs cpu scheduler, where CFQ is on par with the other IO schedulers. > Please have a look to kernel bug #7372: http://bugzilla.kernel.org/show_bug.cgi?id=7372 It seems I encountered the almost same issue. The fix on my side, beside running 2.6.17 (which was working fine for me) was to: 1) have /proc/sys/vm/vfs_cache_pressure=1 2) have /proc/sys/vm/dirty_ratio=1 and /proc/sys/vm/dirty_background_ratio=1 3) have /proc/sys/vm/swappiness=2 4) run Peter Zijlstra: per dirty device throttling patch on the top of 2.6.21.5: http://www.ussg.iu.edu/hypermail/linux/kernel/0706.1/2776.html Hope that helps, -- Brice Figureau