From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934006AbXC0Fn2 (ORCPT ); Tue, 27 Mar 2007 01:43:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S934003AbXC0Fn2 (ORCPT ); Tue, 27 Mar 2007 01:43:28 -0400 Received: from gw.goop.org ([64.81.55.164]:47234 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933986AbXC0Fn1 (ORCPT ); Tue, 27 Mar 2007 01:43:27 -0400 Message-ID: <4608AF01.4060804@goop.org> Date: Mon, 26 Mar 2007 22:43:29 -0700 From: Jeremy Fitzhardinge User-Agent: Thunderbird 1.5.0.10 (X11/20070302) MIME-Version: 1.0 To: Prarit Bhargava CC: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, clalance@redhat.com, mingo@redhat.com, davej@redhat.com, Thilo.Cestonaro.external@fujitsu-siemens.com Subject: Re: [PATCH]: Fix bogus softlockup warning with sysrq-t References: <20070315132247.11291.28827.sendpatchset@prarit.boston.redhat.com> In-Reply-To: <20070315132247.11291.28827.sendpatchset@prarit.boston.redhat.com> Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Prarit Bhargava wrote: > There are some situations when soft lockup warnings are expected in the > kernel. For example, when doing an alt-sysrq-t on a large number of processes, > the dump to console can take a long time and the tasklist_lock is held over > that period. This results in a bogus soft lockup warning. > Wouldn't it be better to just temporarily disable softlockups for the duration? > This patch reworks touch_softlockup_watchdog to touch ALL cpu's > touch_timestamp. It also introduces touch_cpu_softlockup_watchdog to touch > a single cpu's touch_timestamp. Doesn't this mean that if one CPU gets locked up, it will be undetected so long as some other CPU is making progress? I have another pair of softlockup patches in which I try to address: * ignoring time stolen by hypervisors * threads going to sleep tickless for long periods of time I could easy add a "global disable" function, which would allow long sysrq messages, and it would help Thilo with his long flash update freezes. J