From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757416Ab1BQR6x (ORCPT ); Thu, 17 Feb 2011 12:58:53 -0500 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:39140 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753002Ab1BQR6v (ORCPT ); Thu, 17 Feb 2011 12:58:51 -0500 X-Authority-Analysis: v=1.1 cv=+c36koQ5Dcj/1qolKHjtkYAGXvrVJRRiKMp+84F5sLg= c=1 sm=0 a=Lz24SWtJyWAA:10 a=Q9fys5e9bTEA:10 a=OPBmh+XkhLl+Enan7BmTLg==:17 a=meVymXHHAAAA:8 a=VwQbUJbxAAAA:8 a=20KFwNOVAAAA:8 a=6Z8l9LJwAj-ttX9ELcsA:9 a=ykYFAwbwjTH7lnZJAWfpYh2_jwYA:4 a=PUjeQqilurYA:10 a=jeBq3FmKZ4MA:10 a=jEp0ucaQiEUA:10 a=OPBmh+XkhLl+Enan7BmTLg==:117 X-Cloudmark-Score: 0 X-Originating-IP: 67.242.120.143 Subject: Re: [tip:perf/core] tracing: Add unstable sched clock note to the warning From: Steven Rostedt To: Ingo Molnar Cc: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, jolsa@redhat.com, linux-tip-commits@vger.kernel.org In-Reply-To: <20110217171823.GB17058@elte.hu> References: <1296649698-6003-1-git-send-email-jolsa@redhat.com> <1297957180.23343.915.camel@gandalf.stny.rr.com> <20110217171823.GB17058@elte.hu> Content-Type: text/plain; charset="ISO-8859-15" Date: Thu, 17 Feb 2011 12:58:49 -0500 Message-ID: <1297965529.23343.922.camel@gandalf.stny.rr.com> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2011-02-17 at 18:18 +0100, Ingo Molnar wrote: > * Steven Rostedt wrote: > > > On Thu, 2011-02-17 at 15:00 +0000, tip-bot for Jiri Olsa wrote: > > > Commit-ID: 5e38ca8f3ea423442eaafe1b7e206084aa38120a > > > Gitweb: http://git.kernel.org/tip/5e38ca8f3ea423442eaafe1b7e206084aa38120a > > > Author: Jiri Olsa > > > AuthorDate: Wed, 2 Feb 2011 13:28:18 +0100 > > > Committer: Steven Rostedt > > > CommitDate: Tue, 8 Feb 2011 11:57:22 -0500 > > > > > > tracing: Add unstable sched clock note to the warning > > > > > > The warning "Delta way too big" warning might appear on a system with > > > unstable shed clock right after the system is resumed and tracing > > > was enabled during the suspend. > > > > > > Since it's not realy bug, and the unstable sched clock is working > > > fast and reliable otherwise, Steven suggested to keep using the > > > sched clock in any case and just to make note in the warning itself. > > > > > > > > > Peter Zijlstra just informed me on IRC that the commit: > > > > cd7240c0b900eb6d690ccee088a6c9b46dae815a > > x86, tsc, sched: Recompute cyc2ns_offset's during resume from sleep > > states > > > > Prevents the clock from going backwards triggering the warn on. If this > > is the case, I think we can revert this patch. > > > > I'll wait on the original reporters of the bug to find out. If the clock > > does not go backwards when the above commit is applied, then this patch > > is not needed. > > > > If this is the case, do you want me to rebase without it, or should we > > just revert it? > > A revert would be nicer (with an explanation in it), as i've already pushed out the > perc/core tree. > > If you do the revert today against the current perf/core tip (bee96907383e) then i > can pull it in a fast-forward way and we'd minimalize the window. I've just been informed that even with this patch, the clock still goes backwards after resume. -- Steve