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Subject: Re: [OMPI users] Factor of 10 loss in performance with 1.3.x
From: Steve Kargl (sgk_at_[hidden])
Date: 2009-04-10 18:10:35

On Fri, Apr 10, 2009 at 05:10:29PM -0400, Jeff Squyres wrote:
> On Apr 7, 2009, at 4:25 PM, Mostyn Lewis wrote:
> >Does OpenMPI know about the number of CPUS per node for FreeBSD?
> >
> This is exactly the right question: apparently it does not.
> Specifically, it looks like we have a bad configure test in the
> "posix" paffinity component which triggers it to not be built. Hence,
> OMPI *always* thinks there's only 1 processor.
> The setup for how to get the number of processors was totally changed
> between the 1.2 and 1.3 series. I think that this completely explains
> the issue (OMPI didn't have a paffinity component, so it assumed 1
> processor, then it saw that there were 2 processes running, and
> therefore decided that it was running in oversubscribed mode).
> I'll fix. I don't know if it'll make the cut for 1.3.2 or not.

I applied your patch to openmpi-1.3.2a1r20942. It built fine
and the running my test indicate that it fixes the problem.