From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756734Ab0HQLwy (ORCPT ); Tue, 17 Aug 2010 07:52:54 -0400 Received: from bld-mail17.adl2.internode.on.net ([150.101.137.102]:54423 "EHLO mail.internode.on.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755981Ab0HQLwx (ORCPT ); Tue, 17 Aug 2010 07:52:53 -0400 Date: Tue, 17 Aug 2010 21:52:43 +1000 From: Dave Chinner To: Lai Jiangshan Cc: linux-kernel@vger.kernel.org, Steven Rostedt Subject: Re: [tracing, hang] dumping events gets stuck in synchronise_sched Message-ID: <20100817115243.GE7362@dastard> References: <20100817073725.GO10429@dastard> <4C6A4A58.2030904@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4C6A4A58.2030904@cn.fujitsu.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 17, 2010 at 04:37:44PM +0800, Lai Jiangshan wrote: > On 08/17/2010 03:37 PM, Dave Chinner wrote: > > Tracing folks, > > > > I've got a machine stuck with a cpu spinning in a tight loop (the > > new writeback/sync livelock avoidance code is, well, livelocking), > > and I was trying to find out what triggered by using the writeback > > trace events. Unfortunately, I can't dump the trace events because > > it gets stuck here: > > > > > Given that the trace events are there mainly for debugging, this > > seems like a bit of an oversight - hanging a CPU in a tight loop is > > not an uncommon event during code development.... > > > > You can try 'cat trace_pipe', if I did not miss you meaning. I'll try it, but I'm really after the static event list which is why I'm using the trace file rather than trace_pipe. I want the history, not new events as they happen. Cheers, Dave. -- Dave Chinner david@fromorbit.com