Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757453AbZJBRNw (ORCPT ); Fri, 2 Oct 2009 13:13:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753300AbZJBRNv (ORCPT ); Fri, 2 Oct 2009 13:13:51 -0400 Received: from brick.kernel.dk ([93.163.65.50]:33568 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753041AbZJBRNv (ORCPT ); Fri, 2 Oct 2009 13:13:51 -0400 Date: Fri, 2 Oct 2009 19:13:54 +0200 From: Jens Axboe To: Ray Lee Cc: Linus Torvalds , Ingo Molnar , Mike Galbraith , Vivek Goyal , Ulrich Lukas , linux-kernel@vger.kernel.org, containers@lists.linux-foundation.org, dm-devel@redhat.com, nauman@google.com, dpshah@google.com, lizf@cn.fujitsu.com, mikew@google.com, fchecconi@gmail.com, paolo.valente@unimore.it, ryov@valinux.co.jp, fernando@oss.ntt.co.jp, jmoyer@redhat.com, dhaval@linux.vnet.ibm.com, balbir@linux.vnet.ibm.com, righi.andrea@gmail.com, m-ikeda@ds.jp.nec.com, agk@redhat.com, akpm@linux-foundation.org, peterz@infradead.org, jmarchan@redhat.com, riel@redhat.com Subject: Re: IO scheduler based IO controller V10 Message-ID: <20091002171354.GH31616@kernel.dk> References: <20090930202447.GA28236@redhat.com> <1254382405.7595.9.camel@marge.simson.net> <20091001185816.GU14918@kernel.dk> <1254464628.7158.101.camel@marge.simson.net> <20091002080417.GG14918@kernel.dk> <20091002092409.GA19529@elte.hu> <20091002092839.GA26962@kernel.dk> <20091002145610.GD31616@kernel.dk> <2c0942db0910020933l6d312c6ahae0e00619f598b39@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2c0942db0910020933l6d312c6ahae0e00619f598b39@mail.gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1295 Lines: 29 On Fri, Oct 02 2009, Ray Lee wrote: > On Fri, Oct 2, 2009 at 7:56 AM, Jens Axboe wrote: > > In some cases I wish we had a server vs desktop switch, since it would > > decisions on this easier. I know you say that servers care about > > latency, but not at all to the extent that desktops do. Most desktop > > users would gladly give away the top of the performance for latency, > > that's not true of most server users. Depends on what the server does, > > of course. > > If most of the I/O on a system exhibits seeky tendencies, couldn't the > schedulers notice that and use that as the hint for what to optimize? > > I mean, there's no switch better than the actual I/O behavior itself. Heuristics like that have a tendency to fail. What's the cut-off point? Additionally, heuristics based on past process/system behaviour also has a tendency to be suboptimal, since things aren't static. We already look at seekiness of individual processes or groups. IIRC, as-iosched also keeps a per-queue tracking. -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/