Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755048Ab0GUUyS (ORCPT ); Wed, 21 Jul 2010 16:54:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48826 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754678Ab0GUUyR (ORCPT ); Wed, 21 Jul 2010 16:54:17 -0400 From: Jeff Moyer To: Vivek Goyal Cc: linux-kernel@vger.kernel.org, axboe@kernel.dk, nauman@google.com, dpshah@google.com, guijianfeng@cn.fujitsu.com, czoccolo@gmail.com Subject: Re: [PATCH 2/3] cfq-iosched: Implement a tunable group_idle References: <1279739181-24482-1-git-send-email-vgoyal@redhat.com> <1279739181-24482-3-git-send-email-vgoyal@redhat.com> <20100721201318.GH20458@redhat.com> X-PGP-KeyID: 1F78E1B4 X-PGP-CertKey: F6FE 280D 8293 F72C 65FD 5A58 1FF8 A7CA 1F78 E1B4 X-PCLoadLetter: What the f**k does that mean? Date: Wed, 21 Jul 2010 16:54:03 -0400 In-Reply-To: <20100721201318.GH20458@redhat.com> (Vivek Goyal's message of "Wed, 21 Jul 2010 16:13:18 -0400") Message-ID: User-Agent: Gnus/5.110011 (No Gnus v0.11) Emacs/23.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1477 Lines: 44 Vivek Goyal writes: > On Wed, Jul 21, 2010 at 03:40:44PM -0400, Jeff Moyer wrote: >> Vivek Goyal writes: >> >> > o Implement a new tunable group_idle, which allows idling on the group >> > instead of a cfq queue. Hence one can set slice_idle = 0 and not idle >> > on the individual queues but idle on the group. This way on fast storage >> > we can get fairness between groups at the same time overall throughput >> > improves. >> > >> > Signed-off-by: Vivek Goyal >> > --- >> [snip] >> > @@ -1929,13 +1941,21 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd) >> > return; >> > } >> > >> > + /* There are other queues in the group, don't do group idle */ >> > + if (group_idle && cfqq->cfqg->nr_cfqq > 1) >> > + return; >> > + >> > cfq_mark_cfqq_wait_request(cfqq); >> > >> > - sl = cfqd->cfq_slice_idle; >> > + if (group_idle) >> > + sl = cfqd->cfq_group_idle; >> > + else >> > + sl = cfqd->cfq_slice_idle; >> >> What happens when both group_idle and slice_idle are set? > > slice_idle prevails. Notice that "group_idle" is a local variable which > is set to 1 only if we decide not to idle on the cfq queue. Ah, silly me. Cheers, Jeff -- 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/