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SubjectStrange thread behaviour on 8-way x86 machine

I have observed a rather strange behaviour doing a multi-threaded CPU
benchmark on an 8-way machine running 2.4.2 SMP kernel. Even when the
priority is reniced to the highest possible value, I am still unable to reach
more than 50% CPU utilization. My benchmark just creates a bunch of threads
with pthread_create(), and then runs a simple integer computation in each
thread. On a dual with 2.4.3 kernel, and a 4-way with 2.4.2 kernel, I am able
to reach full CPU utilization.

At first glance, it appears to be like some overzealous fairness problem in
the scheduler that is exhibited only when you have more than 4 CPUs. Before I
start scrutinizing the source trying to understand the inner workings of the
scheduler, I would like to get some feedback from people that know something
about the subject. Any ideas/suggestions would be appreciated.

MySQL Development Team
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/ |/ /_ __/ __/ __ \/ / Sasha Pachev <>
/ /|_/ / // /\ \/ /_/ / /__ MySQL AB,
/_/ /_/\_, /___/\___\_\___/ Provo, Utah, USA
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