From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S937966AbXGSPKc (ORCPT ); Thu, 19 Jul 2007 11:10:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759763AbXGSPKH (ORCPT ); Thu, 19 Jul 2007 11:10:07 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:42182 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758349AbXGSPKF (ORCPT ); Thu, 19 Jul 2007 11:10:05 -0400 Date: Thu, 19 Jul 2007 17:09:55 +0200 From: Ingo Molnar To: Jeremy Fitzhardinge Cc: Andrew Morton , linux-kernel@vger.kernel.org, Linus Torvalds , stable@kernel.org, Greg KH , Chris Wright Subject: Re: [patch] fix the softlockup watchdog to actually work Message-ID: <20070719150955.GA19373@elte.hu> References: <20070717114453.GA8212@elte.hu> <469CCF8F.4010107@goop.org> <20070717154934.GA24231@elte.hu> <20070719002231.069ebbdd.akpm@linux-foundation.org> <20070719075152.GB12760@elte.hu> <469F75AF.5080000@goop.org> <20070719143528.GA8278@elte.hu> <469F793E.6030006@goop.org> <20070719145058.GA11971@elte.hu> <469F7D7A.204@goop.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <469F7D7A.204@goop.org> User-Agent: Mutt/1.5.14 (2007-02-12) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.0.3 -1.0 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 * Jeremy Fitzhardinge wrote: > Ingo Molnar wrote: > > no, the return value after idling can be completely random on some > > boxes, on a 64-bit scale - triggering the softlockup watchdog randomly. > > (some boxes return random TSC values, etc.) Again, it's fine for the > > scheduler's purpose, that's why i named it sched_clock(). > > > > the proper clocksource use within the kernel is ktime_get() [or > > ktime_get_ts()]. Do not abuse sched_clock() for such things. > > Well, my observation is that both softlockup and the scheduler really > want to measure unstolen time, so it seemed to me that sched_clock was > a nice common place to implement that, rather than implementing a > whole new time interface. At the time that seemed OK, and nobody had > any objections. yeah. But then it should not be using sched_clock() but CFS's new rq_clock() method - which does try to construct a globally valid timesource out of sched_clock(). [that fix is not backportable though] Ingo