From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756656Ab0HQIdh (ORCPT ); Tue, 17 Aug 2010 04:33:37 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:52371 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1754009Ab0HQIdg (ORCPT ); Tue, 17 Aug 2010 04:33:36 -0400 Message-ID: <4C6A4A58.2030904@cn.fujitsu.com> Date: Tue, 17 Aug 2010 16:37:44 +0800 From: Lai Jiangshan User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.9) Gecko/20100423 Thunderbird/3.0.4 MIME-Version: 1.0 To: Dave Chinner CC: linux-kernel@vger.kernel.org, Steven Rostedt Subject: Re: [tracing, hang] dumping events gets stuck in synchronise_sched References: <20100817073725.GO10429@dastard> In-Reply-To: <20100817073725.GO10429@dastard> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Lai