Idle core on overloaded CPU?

From: Carsten Aulbert
Date: Thu Oct 23 2008 - 08:38:31 EST


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

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:
), but if not could this be a scheduling bug?

Thanks for any hint


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