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Message-ID: <49006A30.7030208@aei.mpg.de>
Date:	Thu, 23 Oct 2008 14:12:32 +0200
From:	Carsten Aulbert <carsten.aulbert@....mpg.de>
To:	linux-kernel@...r.kernel.org
CC:	Henning Fehrmann <henning.fehrmann@....mpg.de>
Subject: Idle core on overloaded CPU?

Hi,

on Intel X3220 CPU based systems (4 physical cores) I came across the
following thing (Debian etch, with vanilla kernel 2.6.25.9):

starting the following:
$ screen -d -m stress -c 2
$ nice -19 screen -d -m stress -c 4

This causes two cores to be 100% busy in user state and one core to be
busy in 100% nice state. However, the remaining core is idle. Even
watching it over longer stretches of time, the situation remains static.

I guess it's a kernel misconfiguration on my part (config available here:
https://n0.aei.uni-hannover.de/linux/kernel/config-2.6.25.9-nodes
), but if not could this be a scheduling bug?

Thanks for any hint

Cheers

Carsten
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