Re: CPU affinity

Mathias Froehlich (frohlich@na.uni-tuebingen.de)
Thu, 15 Apr 1999 09:57:52 +0200 (MET DST)

> On Wed, 14 Apr 1999, Rik van Riel wrote:
>
> > I think it won't affect the code path or the scheduling
> > behaviour very much, except for the fact that it'll cause
> > processes to stick to their CPU much better.

> 'much better'?. Do you have any testcase that shows that we do not stick
> to CPUs well enough? I actually have recorded traces of full kernel builds
> and the like, and the number of 'bad' CPU switches was zero. I'm getting
> slightly tired of claims like the above, this isnt a Microsoft trade show
> after all ...

Yes I have a testcase. I usually use xosview to visualize the CPU
usage on my dual PII system. When I start a pure numbercrunching job,
I can see how the numbercruncher is sheduled out by xosview by any
screen update of xosview. The kernel sees then an idle CPU and
schedules the numbercruncher onto the other CPU. This looks like a
__perfect__ "numbercruncing ping pong".

Regards,

Mathias Froehlich

-- 
Mathias Fr"ohlich              e-mail: frohlich@na.uni-tuebingen.de
Institut f"ur Mathematik, Universit"at T"ubingen, D-72076 T"ubingen


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