Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753177Ab3DZEkQ (ORCPT ); Fri, 26 Apr 2013 00:40:16 -0400 Received: from oproxy9.bluehost.com ([69.89.24.6]:41123 "HELO oproxy9.bluehost.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751090Ab3DZEkO (ORCPT ); Fri, 26 Apr 2013 00:40:14 -0400 Message-ID: <1366951210.7911.28.camel@Wailaba2> Subject: Re: [PATCH] process cputimer is moving faster than its corresponding clock From: Olivier Langlois To: KOSAKI Motohiro Cc: Frederic Weisbecker , Peter Zijlstra , Ingo Molnar , Thomas Gleixner , schwidefsky@de.ibm.com, Steven Rostedt , LKML Date: Fri, 26 Apr 2013 00:40:10 -0400 In-Reply-To: References: <1365184746.874.103.camel@Wailaba2> <1365593710.30071.52.camel@laptop> <1365608911.707.65.camel@Wailaba2> <1365763837.17140.52.camel@laptop> <1365782115.17140.68.camel@laptop> Organization: Trillion01 Inc Content-Type: text/plain; charset="ISO-8859-1" X-Mailer: Evolution 3.8.1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-Identified-User: {5686:box610.bluehost.com:olivierl:trillion01.com} {sentby:smtp auth 173.178.230.31 authed with olivier@trillion01.com} Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1282 Lines: 32 On Fri, 2013-04-19 at 11:08 -0700, KOSAKI Motohiro wrote: > On Fri, Apr 19, 2013 at 10:38 AM, KOSAKI Motohiro > wrote: > >> I feel we are hitting the same issue than this patch: > >> https://lkml.org/lkml/2013/4/5/116 > >> > >> I'm adding Kosaki in Cc, who proposed roughly the same fix. > > > > Thanks to CCing. I'm now sitting LSF and I can't read whole tons emails. > > However the fix is definitely same and I definitely agree this approach. > > > > thank you. > > And if I understand correctly, update_gt_cputime() is no longer > necessary after this patch because time never makes backward. > > What do you think? Kosaki, I would tend to say that what you propose is exact. After having added the task deltas I was puzzled to see the cputimer still moving faster than the process clock. I was seeing it with the the help of printk statement inside update_gt_cputime(). After nailing down the last remaining cause of that inside sched/core.c, I have never seen after the cputimer being in advance. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/