From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756146AbXKBPZt (ORCPT ); Fri, 2 Nov 2007 11:25:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754700AbXKBPZn (ORCPT ); Fri, 2 Nov 2007 11:25:43 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:47961 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754115AbXKBPZm (ORCPT ); Fri, 2 Nov 2007 11:25:42 -0400 Date: Fri, 2 Nov 2007 16:25:29 +0100 From: Ingo Molnar To: Balbir Singh Cc: Peter Zijlstra , Thomas Gleixner , linux kernel mailing list Subject: Re: delayacct regression in 2.6.24 git Message-ID: <20071102152529.GB20134@elte.hu> References: <472B2908.7020507@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <472B2908.7020507@linux.vnet.ibm.com> User-Agent: Mutt/1.5.16 (2007-06-09) 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=3.1.7-deb -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Balbir Singh wrote: > Hi, Ingo, > > I missed commit 75d4ef16a6aa84f708188bada182315f80aab6fa > "sched: fix delay accounting performance regression" > > Without these changes, I find that delay accounting does > not work as expected, I see zeros in the field for virtual,delay > and count(s). > > CPU count real total virtual total delay total > 0 535861848 0 0 > > > This breaks existing delay accounting behaviour. > > Am I missing something? delay accounting was causing context-switch slowdown because it called sched_clock() explicitly - but indeed my fix to that is wrong ... how about reverting the change but also using rq->clock instead of sched_clock()? Ingo