linux-kernel - Re: High priority tasks break SMP balancer?

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Message-ID: <4734F397.7080802@gmx.net>
Date:	Sat, 10 Nov 2007 00:56:07 +0100
From:	Cyrus Massoumi <cyrusm@....net>
To:	Micah Dowty <micah@...are.com>
CC:	linux-kernel@...r.kernel.org
Subject: Re: High priority tasks break SMP balancer?

Hi Micah

> On my machine (2-way Opteron with a vanilla 2.6.23.1 kernel) this test
> program will reliably put the scheduler into a state where one CPU has
> both of the busy-looping processes in its runqueue, and the other CPU
> is usually idle. The usually-idle CPU will have a very high cpu_load,
> as reported by /proc/sched_debug.

I tried your program on my machine (C2D, 2.6.17, O(1) scheduler).

Both CPUs are 100% busy all the time. Each busy-looping thread is 
running on its own CPU. I've been watching top output for 10 minutes, 
the spreading is stable and the threads don't bounce at all.

greetings
Cyrus

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