From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S938385AbXGSOf4 (ORCPT ); Thu, 19 Jul 2007 10:35:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756807AbXGSOfq (ORCPT ); Thu, 19 Jul 2007 10:35:46 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:46463 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753029AbXGSOfp (ORCPT ); Thu, 19 Jul 2007 10:35:45 -0400 Date: Thu, 19 Jul 2007 16:35:28 +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: <20070719143528.GA8278@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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <469F75AF.5080000@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=3.1.7-deb -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: > How reliable does it need to be? All we need is to measure "about 10 > seconds"; if we can't get that out of it, how can it be good for > anything else? sched_clock(), as its name suggests it, is meant for the scheduler's use. The scheduler generally only needs to measure time when the CPU is busy - not across idle periods. So sched_clock() can (and will) break across certain types of ACPI idle methods. Ingo