From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753508AbYIEQPz (ORCPT ); Fri, 5 Sep 2008 12:15:55 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754033AbYIEQPg (ORCPT ); Fri, 5 Sep 2008 12:15:36 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:54083 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754016AbYIEQPf (ORCPT ); Fri, 5 Sep 2008 12:15:35 -0400 Date: Fri, 5 Sep 2008 18:15:16 +0200 From: Ingo Molnar To: Peter Zijlstra Cc: balbir@linux.vnet.ibm.com, Spencer Candland , dmitry.adamushko@gmail.com, linux-kernel@vger.kernel.org Subject: Re: Still seeing decreasing stime/utime Message-ID: <20080905161516.GO10292@elte.hu> References: <48B5C4C7.8040509@bluehost.com> <48B66BCC.8030207@linux.vnet.ibm.com> <48B702FA.8060308@bluehost.com> <20080828224502.GA1540@balbir.in.ibm.com> <48B859C8.5000001@bluehost.com> <48B8E102.5050503@linux.vnet.ibm.com> <1220095656.8426.23.camel@twins> <20080830135557.GA24039@balbir.in.ibm.com> <1220110327.14894.40.camel@lappy.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1220110327.14894.40.camel@lappy.programming.kicks-ass.net> 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 * Peter Zijlstra wrote: > On Sat, 2008-08-30 at 19:25 +0530, Balbir Singh wrote: > > * Peter Zijlstra [2008-08-30 13:27:36]: > > > > > On Sat, 2008-08-30 at 11:26 +0530, Balbir Singh wrote: > > > > Spencer Candland wrote: > > > > >> Here is an experimental patch (I've just compiled and booted a machine > > > > >> with it, I am unable to reproduce your problem), could you please test > > > > >> it for me and see if it helps solve the problem > > > > > > > > > > Looks like this fixed it. I have been testing this for the last 16 > > > > > hours and everything is looking good. > > > > > > > > > > > > > Excellent! Ingo, Peter, do you like the patch? If so, could you please pick it > > > > up Ingo. I think we should even push the fix to stable releases. > > > > > > Looks good, except for the issue you yourself earlier raised, a few of > > > those functions looks too large to be inlined. > > > > > > > Here's the updated revision with task_*time functions moved to sched.c > > and inlining removed, except for task_gtime(). I've compiled and > > booted a machine (x86_64) with this patch applied. > > > > Reported-by: spencer@bluehost.com > > > > Spencer reported a problem where utime and stime were going negative despite > > the fixes in commit b27f03d4bdc145a09fb7b0c0e004b29f1ee555fa. The suspected > > reason for the problem is that signal_struct maintains it's own utime and > > stime (of exited tasks), these are not updated using the new task_utime() > > routine, hence sig->utime can go backwards and cause the same problem > > to occur (sig->utime, adds tsk->utime and not task_utime()). This patch > > fixes the problem > > > > TODO: using max(task->prev_utime, derived utime) works for now, but a more > > generic solution is to implement cputime_max() and use the cputime_gt() > > function for comparison. > > > > Comments? > > > > Signed-off-by: Balbir Singh > > Thanks Balbir! > > Acked-by: Peter Zijlstra applied to tip/sched/urgent, thanks! Ingo