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SubjectRe: linux thread scheduling
Xin Tong wrote:

> I have a program that spawns 3 threads and there is a great deal of
> sharing among the three threads. they all read/update a couple of
> shared variables.
> I run this on nehalem (8 cores, 4 core in each physical package), I
> find that running the 3 threads on core 0, 1, 2 (using
> pthread_setaffinitiy) gives much better results, this is because the
> cache coherency protocol performs much better on the same package.
> However, if I leave Linux (Suse Enterprise) to schedule it. it gives
> much worse performance, i suspect that linux is scheduling the 3
> threads across the physical packages ( 2 on one package, 1 on
> another). Is this possible ? why does linux do this ?

the following paper on cpu schedulers was posted recently. Maybe it gives you
a starting point.

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