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Date: Fri, 22 Oct 2010 10:16:40 +0200
From: Tejun Heo <tj@kernel.org>
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To: Jason Baron <jbaron@redhat.com>, Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Ingo Molnar <mingo@elte.hu>, Steven Rostedt <rostedt@goodmis.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>, "H. Peter Anvin" <hpa@zytor.com>,
        Arnaldo Carvalho de Melo <acme@redhat.com>
Subject: Re: [PATCH][GIT PULL] tracing: Fix compile issue for trace_sched_wakeup.c
References: <1287508282.16971.386.camel@gandalf.stny.rr.com> <20101019184111.GA17266@elte.hu> <20101020154045.GA18353@elte.hu> <1287659656.16971.573.camel@gandalf.stny.rr.com> <20101021112614.GB26984@elte.hu> <20101022014441.GA1948@redhat.com>
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Hello,

On 10/22/2010 03:44 AM, Jason Baron wrote:
> (adding Tejun to the 'cc list)
> 
> I finally found that we actually continue to run after the above
> apparent 'hang'. That is, we continue to make progress updating the jump
> labels. And doing a dump of all the system tasks at the time of the hang
> showed the processes in various places besides the stop machine threads.
> Thus, I thought that perhaps, for some reason the stop machine threads
> weren't being scheduled.
> 
> Thus, I tried commenting out the special scheduling that is set up for
> stop machine threads, and that fixed the hang. I haven't yet looked into
> what might be going wrong with that scheduling...but maybe somebody else
> knows...

I'm afraid I don't have much idea about the new scheduling class.  I
liked the idea but Peter did all the hard working on it.  Peter?

Thanks.

-- 
tejun