From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Subject: Re: [Bug #12650] Strange load average and ksoftirqd behavior with 2.6.29-rc2-git1 Date: Wed, 18 Feb 2009 01:38:01 +0100 Message-ID: <20090218003801.GD25856@elte.hu> References: <87ljs6pmao.fsf@free.fr> <20090216132151.GA17996@elte.hu> <20090216160613.GA6785@linux.vnet.ibm.com> <20090216185616.GB6785@linux.vnet.ibm.com> <20090216200923.GA28938@elte.hu> <20090216223944.GF6785@linux.vnet.ibm.com> <20090217043422.GA5836@nowhere> <20090217151046.GB6761@linux.vnet.ibm.com> <20090217223741.GC5194@nowhere> <20090217224826.GO6761@linux.vnet.ibm.com> Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: <20090217224826.GO6761-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org> Sender: kernel-testers-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: "Paul E. McKenney" Cc: Frederic Weisbecker , Damien Wyart , Peter Zijlstra , Mike Galbraith , "Rafael J. Wysocki" , Linux Kernel Mailing List , Kernel Testers List * Paul E. McKenney wrote: > No, it was my confusion -- I later realized that your data > above meant that the force-quiescent-state code path was not > being heavily exercised. So no need for this trace! Do you have any theory for why RCU was activated every 100-200 microseconds, resulting in 20% ksoftirqd CPU use - and why the problem went away with classic-rcu? Ingo From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754557AbZBRAiV (ORCPT ); Tue, 17 Feb 2009 19:38:21 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751660AbZBRAiM (ORCPT ); Tue, 17 Feb 2009 19:38:12 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:56681 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751592AbZBRAiL (ORCPT ); Tue, 17 Feb 2009 19:38:11 -0500 Date: Wed, 18 Feb 2009 01:38:01 +0100 From: Ingo Molnar To: "Paul E. McKenney" Cc: Frederic Weisbecker , Damien Wyart , Peter Zijlstra , Mike Galbraith , "Rafael J. Wysocki" , Linux Kernel Mailing List , Kernel Testers List Subject: Re: [Bug #12650] Strange load average and ksoftirqd behavior with 2.6.29-rc2-git1 Message-ID: <20090218003801.GD25856@elte.hu> References: <87ljs6pmao.fsf@free.fr> <20090216132151.GA17996@elte.hu> <20090216160613.GA6785@linux.vnet.ibm.com> <20090216185616.GB6785@linux.vnet.ibm.com> <20090216200923.GA28938@elte.hu> <20090216223944.GF6785@linux.vnet.ibm.com> <20090217043422.GA5836@nowhere> <20090217151046.GB6761@linux.vnet.ibm.com> <20090217223741.GC5194@nowhere> <20090217224826.GO6761@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090217224826.GO6761@linux.vnet.ibm.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean 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=3.2.3 -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 * Paul E. McKenney wrote: > No, it was my confusion -- I later realized that your data > above meant that the force-quiescent-state code path was not > being heavily exercised. So no need for this trace! Do you have any theory for why RCU was activated every 100-200 microseconds, resulting in 20% ksoftirqd CPU use - and why the problem went away with classic-rcu? Ingo