Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756758AbZJBQh6 (ORCPT ); Fri, 2 Oct 2009 12:37:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756645AbZJBQh6 (ORCPT ); Fri, 2 Oct 2009 12:37:58 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:50848 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756386AbZJBQh5 (ORCPT ); Fri, 2 Oct 2009 12:37:57 -0400 Date: Fri, 2 Oct 2009 18:37:07 +0200 From: Ingo Molnar To: Mike Galbraith Cc: Jens Axboe , 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, torvalds@linux-foundation.org, riel@redhat.com Subject: Re: IO scheduler based IO controller V10 Message-ID: <20091002163707.GB12546@elte.hu> References: <20090927164235.GA23126@kernel.dk> <1254340730.7695.32.camel@marge.simson.net> <1254341139.7695.36.camel@marge.simson.net> <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> <1254476214.11022.8.camel@marge.simson.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1254476214.11022.8.camel@marge.simson.net> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1634 Lines: 42 * Mike Galbraith wrote: > On Fri, 2009-10-02 at 11:24 +0200, Ingo Molnar wrote: > > * Jens Axboe wrote: > > > > > It's not hard to make the latency good, the hard bit is making sure we > > > also perform well for all other scenarios. > > > > Looking at the numbers from Mike: > > > > | dd competing against perf stat -- konsole -e exec timings, 5 back to > > | back runs > > | Avg > > | before 9.15 14.51 9.39 15.06 9.90 11.6 > > | after [+patch] 1.76 1.54 1.93 1.88 1.56 1.7 > > > > _PLEASE_ make read latencies this good - the numbers are _vastly_ > > better. We'll worry about the 'other' things _after_ we've reached good > > latencies. > > > > I thought this principle was a well established basic rule of Linux > > IO scheduling. Why do we have to have a 'latency vs. bandwidth' > > discussion again and again? I thought latency won hands down. > > Just a note: In the testing I've done so far, we're better off today > than ever, [...] Definitely so, and a couple of months ago i've sung praises of that progress on the IO/fs latencies front: http://lkml.org/lkml/2009/4/9/461 ... but we are greedy bastards and dont define excellence by how far down we have come from but by how high we can still climb ;-) Ingo -- 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/