Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756811AbZJBPcJ (ORCPT ); Fri, 2 Oct 2009 11:32:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756020AbZJBPcI (ORCPT ); Fri, 2 Oct 2009 11:32:08 -0400 Received: from mail.gmx.net ([213.165.64.20]:45776 "HELO mail.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1755931AbZJBPcH (ORCPT ); Fri, 2 Oct 2009 11:32:07 -0400 X-Authenticated: #14349625 X-Provags-ID: V01U2FsdGVkX1907+UvN8N0J9p1oNK4y+AtBiTaLj7158MXKQ7wiu +sY2X40vcpwyWd Subject: Re: IO scheduler based IO controller V10 From: Mike Galbraith To: Corrado Zoccolo Cc: Vivek Goyal , Jens Axboe , Ingo Molnar , 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 In-Reply-To: <4e5e476b0910020827s23e827b1n847c64e355999d4a@mail.gmail.com> References: <200910021255.27689.czoccolo@gmail.com> <20091002124921.GA4494@redhat.com> <4e5e476b0910020827s23e827b1n847c64e355999d4a@mail.gmail.com> Content-Type: text/plain Date: Fri, 02 Oct 2009 17:32:00 +0200 Message-Id: <1254497520.10392.11.camel@marge.simson.net> Mime-Version: 1.0 X-Mailer: Evolution 2.24.1.1 Content-Transfer-Encoding: 7bit X-Y-GMX-Trusted: 0 X-FuHaFi: 0.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2121 Lines: 52 On Fri, 2009-10-02 at 17:27 +0200, Corrado Zoccolo wrote: > On Fri, Oct 2, 2009 at 2:49 PM, Vivek Goyal wrote: > > On Fri, Oct 02, 2009 at 12:55:25PM +0200, Corrado Zoccolo wrote: > > > > Actually I am not touching this code. Looking at the V10, I have not > > changed anything here in idling code. > > I based my analisys on the original patch: > http://lkml.indiana.edu/hypermail/linux/kernel/0907.1/01793.html > > Mike, can you confirm which version of the fairness patch did you use > in your tests? That would be this one-liner. o CFQ provides fair access to disk in terms of disk time used to processes. Fairness is provided for the applications which have their think time with in slice_idle (8ms default) limit. o CFQ currently disables idling for seeky processes. So even if a process has think time with-in slice_idle limits, it will still not get fair share of disk. Disabling idling for a seeky process seems good from throughput perspective but not necessarily from fairness perspecitve. 0 Do not disable idling based on seek pattern of process if a user has set /sys/block//queue/iosched/fairness = 1. Signed-off-by: Vivek Goyal --- block/cfq-iosched.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Index: linux-2.6/block/cfq-iosched.c =================================================================== --- linux-2.6.orig/block/cfq-iosched.c +++ linux-2.6/block/cfq-iosched.c @@ -1953,7 +1953,7 @@ cfq_update_idle_window(struct cfq_data * enable_idle = old_idle = cfq_cfqq_idle_window(cfqq); if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle || - (cfqd->hw_tag && CIC_SEEKY(cic))) + (!cfqd->cfq_fairness && cfqd->hw_tag && CIC_SEEKY(cic))) enable_idle = 0; else if (sample_valid(cic->ttime_samples)) { if (cic->ttime_mean > cfqd->cfq_slice_idle) -- 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/