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Subject: Re: [OMPI users] Hybrid program
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2008-12-02 12:52:03


On Dec 2, 2008, at 11:27 AM, Edgar Gabriel wrote:

> so I ran a couple of tests today and I can not confirm your
> statement. I wrote simple a simple test code where a process first
> sets an affinity mask and than spawns a number of threads. The
> threads modify the affinity mask and every thread ( including the
> master thread) print out there affinity mask at the end.
>
> With sched_getaffinity() and sched_setaffinity() it was indeed such
> that the master thread had the same affinity mask as the thread that
> it spawned. This means, that the modification of the affinity mask
> by a new thread in fact did affect the master thread.
>
> Executing the same codesquence however using the libnuma calls, the
> master thread however was not affected by the new affinity mask of
> the children. So clearly, libnuma must be doing something differently.

What distro/version of Linux are you using, and what version of libnuma?

Libnuma v2.0.x very definitely is just a wrapper around the syscall
for sched_setaffinity(). I downloaded it from:

     ftp://oss.sgi.com/www/projects/libnuma/download

-- 
Jeff Squyres
Cisco Systems