Re: High priority tasks break SMP balancer?

From: Cyrus Massoumi
Date: Fri Nov 09 2007 - 18:55:37 EST


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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