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Subject: Re: Very high CPU values in top on idle system (3.0-rc1)
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Markus Trippelsdorf <markus@trippelsdorf.de>
Cc: linux-kernel@vger.kernel.org
In-Reply-To: <20110530173916.GA1746@x4.trippels.de>
References: <20110530173916.GA1746@x4.trippels.de>
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Date: Mon, 30 May 2011 20:05:43 +0200
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On Mon, 2011-05-30 at 19:39 +0200, Markus Trippelsdorf wrote:
> I get very high CPU values when I run 'top' on my (mostly) idle system
> with 3.0-rc1. For example mpd was always in the 1-2% range and is now
> constantly over 50%. 
> 
> This is caused by:
> 
> commit 317f394160e9beb97d19a84c39b7e5eb3d7815a8
> Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Date:   Tue Apr 5 17:23:58 2011 +0200
> 
>     sched: Move the second half of ttwu() to the remote cpu
> 
> When I revert the above I see sane CPU values again.

So: echo NO_TTWU_QUEUE > /debug/sched_features, also cures it?

What architecture, what .config, and can you see it with anything other
than mpd (yum search mpd, only seems to result in mpd clients not the
actual server).