From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756603Ab3LECoY (ORCPT ); Wed, 4 Dec 2013 21:44:24 -0500 Received: from e37.co.us.ibm.com ([32.97.110.158]:41531 "EHLO e37.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756250Ab3LECoU (ORCPT ); Wed, 4 Dec 2013 21:44:20 -0500 Date: Wed, 4 Dec 2013 18:44:14 -0800 From: "Paul E. McKenney" To: Dave Jones , Linux Kernel Subject: Re: lots of brief rcu stalls. Message-ID: <20131205024414.GL15492@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20131204232838.GA25592@redhat.com> <20131205001614.GI15492@linux.vnet.ibm.com> <20131205012206.GA31349@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131205012206.GA31349@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13120502-7164-0000-0000-000003F3D3A5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 04, 2013 at 08:22:06PM -0500, Dave Jones wrote: > On Wed, Dec 04, 2013 at 04:16:14PM -0800, Paul E. McKenney wrote: > > On Wed, Dec 04, 2013 at 06:28:38PM -0500, Dave Jones wrote: > > > Paul, > > > I'm seeing this happening more and more lately... > > > > > > [ 771.786462] INFO: rcu_preempt detected stalls on CPUs/tasks: > > > [ 771.786552] Tasks blocked on level-0 rcu_node (CPUs 0-3): > > > [ 771.786574] Tasks blocked on level-0 rcu_node (CPUs 0-3): > > > [ 771.786595] (detected by 0, t=6502 jiffies, g=20611, c=20610, q=0) > > > [ 771.786620] INFO: Stall ended before state dump start > > > [ 966.724546] INFO: rcu_preempt detected stalls on CPUs/tasks: > > > [ 966.724854] Tasks blocked on level-0 rcu_node (CPUs 0-3): > > > [ 966.724931] Tasks blocked on level-0 rcu_node (CPUs 0-3): > > > [ 966.725005] (detected by 0, t=26007 jiffies, g=20611, c=20610, q=0) > > > [ 966.725093] INFO: Stall ended before state dump start > > > [ 1161.661459] INFO: rcu_preempt detected stalls on CPUs/tasks: > > > [ 1161.661763] Tasks blocked on level-0 rcu_node (CPUs 0-3): > > > [ 1161.661840] Tasks blocked on level-0 rcu_node (CPUs 0-3): > > > [ 1161.661915] (detected by 0, t=45512 jiffies, g=20611, c=20610, q=0) > > > [ 1161.662001] INFO: Stall ended before state dump start > > > [ 1356.598205] INFO: rcu_preempt detected stalls on CPUs/tasks: > > > [ 1356.598513] Tasks blocked on level-0 rcu_node (CPUs 0-3): > > > [ 1356.598590] Tasks blocked on level-0 rcu_node (CPUs 0-3): > > > [ 1356.598664] (detected by 0, t=65017 jiffies, g=20611, c=20610, q=0) > > > [ 1356.598751] INFO: Stall ended before state dump start > > > [ 1551.536099] INFO: rcu_preempt detected stalls on CPUs/tasks: > > > [ 1551.536408] Tasks blocked on level-0 rcu_node (CPUs 0-3): > > > [ 1551.536485] Tasks blocked on level-0 rcu_node (CPUs 0-3): > > > [ 1551.536559] (detected by 0, t=84522 jiffies, g=20611, c=20610, q=0) > > > [ 1551.536645] INFO: Stall ended before state dump start > > > > > > While it's apparently a non-problem, it's pretty noisy. > > > Any ideas? > > > > Does the following help? > > Seems so so far! Keeping fingers firmly crossed... Thanx, Paul