Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753776Ab1EaM4Z (ORCPT ); Tue, 31 May 2011 08:56:25 -0400 Received: from s15228384.onlinehome-server.info ([87.106.30.177]:45591 "EHLO mail.x86-64.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751234Ab1EaM4Y (ORCPT ); Tue, 31 May 2011 08:56:24 -0400 Date: Tue, 31 May 2011 14:56:21 +0200 From: Borislav Petkov To: a.p.zijlstra@chello.nl Cc: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, markus@trippelsdorf.de, tglx@linutronix.de, mingo@elte.hu, linux-tip-commits@vger.kernel.org Subject: Re: [tip:sched/urgent] sched: Fix cross-cpu clock sync on remote wakeups Message-ID: <20110531125621.GA24439@gere.osrc.amd.com> References: <1306835745.2353.3.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1869 Lines: 51 Hey Peter, On Tue, May 31, 2011 at 12:31:20PM +0000, tip-bot for Peter Zijlstra wrote: > Commit-ID: f01114cb59d670e9b4f2c335930dd57db96e9360 > Gitweb: http://git.kernel.org/tip/f01114cb59d670e9b4f2c335930dd57db96e9360 > Author: Peter Zijlstra > AuthorDate: Tue, 31 May 2011 12:26:55 +0200 > Committer: Ingo Molnar > CommitDate: Tue, 31 May 2011 14:19:56 +0200 > > sched: Fix cross-cpu clock sync on remote wakeups > > Markus reported that commit 317f394160e ("sched: Move the second half > of ttwu() to the remote cpu") caused some accounting funnies on his AMD > Phenom II X4, such as weird 'top' results. > > It turns out that this is due to non-synced TSC this would mean that his machine doesn't pass the TSC sync check at boot but that's a F10h and they usu. have synchronized TSCs? I'm confused. > and the queued remote > wakeups stopped coupeling the two relevant cpu clocks, which leads to > wakeups seeing time jumps, which in turn lead to skewed runtime stats. > > Add an explicit call to sched_clock_cpu() to couple the per-cpu clocks > to restore the normal flow of time. > > Reported-and-tested-by: Markus Trippelsdorf > Signed-off-by: Peter Zijlstra > Link: http://lkml.kernel.org/r/1306835745.2353.3.camel@twins > Signed-off-by: Ingo Molnar Thanks. -- Regards/Gruss, Boris. Advanced Micro Devices GmbH Einsteinring 24, 85609 Dornach General Managers: Alberto Bozzo, Andrew Bowd Registration: Dornach, Gemeinde Aschheim, Landkreis Muenchen Registergericht Muenchen, HRB Nr. 43632 -- 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/