From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vivek Goyal Subject: Re: [RFC PATCH 0/3] block: Fix fsync slowness with CFQ cgroups Date: Tue, 28 Jun 2011 10:47:44 -0400 Message-ID: <20110628144744.GF17552@redhat.com> References: <1309205864-13124-1-git-send-email-vgoyal@redhat.com> <4E09B457.9050800@parallels.com> <20110628134500.GD17552@redhat.com> <4E09E871.8040600@parallels.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "linux-kernel@vger.kernel.org" , "jaxboe@fusionio.com" , "linux-fsdevel@vger.kernel.org" , "linux-ext4@vger.kernel.org" , "jmoyer@redhat.com" To: Konstantin Khlebnikov Return-path: Received: from mx1.redhat.com ([209.132.183.28]:50638 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758040Ab1F1Orr (ORCPT ); Tue, 28 Jun 2011 10:47:47 -0400 Content-Disposition: inline In-Reply-To: <4E09E871.8040600@parallels.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Tue, Jun 28, 2011 at 06:42:57PM +0400, Konstantin Khlebnikov wrote: > Vivek Goyal wrote: > >On Tue, Jun 28, 2011 at 03:00:39PM +0400, Konstantin Khlebnikov wrote: > >>Vivek Goyal wrote: > >>>This patch series seems to be working for me. I did testing for ext4 only. > >>>This series is based on for-3.1/core branch of Jen's block tree. > >>>Konstantin, can you please give it a try and see if it fixes your > >>>issue. > >> > >>It works for me too, for ext3 and ext4, on top 3.0-rc5, after these trivial fixes: > >> > >>--- a/block/cfq-iosched.c > >>+++ b/block/cfq-iosched.c > >>@@ -1511,7 +1519,7 @@ static void cfq_add_rq_rb(struct request *rq) > >> * if that happens, put the alias on the dispatch list > >> */ > >> while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL) > >>- cfq_dispatch_insert(cfqd->queue, __alias); > >>+ cfq_dispatch_insert(cfqd->queue, __alias, false); > >> > >> if (!cfq_cfqq_on_rr(cfqq)) > >> cfq_add_cfqq_rr(cfqd, cfqq); > >>@@ -3797,12 +3797,11 @@ cfq_set_depends_on_task(struct request_queue *q, struct task_struct *tsk) > >> */ > >> rcu_read_lock(); > >> if (task_blkio_cgroup(current) == task_blkio_cgroup(tsk)) > >>- return; > >>- rcu_read_unlock(); > >>+ goto out_unlock_rcu; > >> > >> cic = cfq_cic_lookup(cfqd, current->io_context); > >> if (!cic) > >>- return; > >>+ goto out_unlock_rcu; > > > >You have done this change because you want to keep cfq_cic_lookup() also > >in rcu read side critical section? I am assuming that it works even > >without this. Though keeping it under rcu is probably more correct as > >cic objects are freed in rcu manner. > > No, your just forgot to relese rcu in case task_blkio_cgroup(current) == task_blkio_cgroup(tsk) Oh, that's right. Thanks for catching this. I will fix it. Thanks Vivek