From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936219AbXGSOlw (ORCPT ); Thu, 19 Jul 2007 10:41:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756807AbXGSOln (ORCPT ); Thu, 19 Jul 2007 10:41:43 -0400 Received: from gw.goop.org ([64.81.55.164]:58703 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756800AbXGSOlm (ORCPT ); Thu, 19 Jul 2007 10:41:42 -0400 Message-ID: <469F77F0.8040407@goop.org> Date: Thu, 19 Jul 2007 07:40:48 -0700 From: Jeremy Fitzhardinge User-Agent: Thunderbird 2.0.0.4 (X11/20070615) MIME-Version: 1.0 To: Ingo Molnar 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 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> In-Reply-To: <20070719143528.GA8278@elte.hu> X-Enigmail-Version: 0.95.2 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Ingo Molnar 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. > Doesn't that mean it will mis-measure process idle times? Is that a problem? J