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Subject: Re: [OMPI users] Factor of 10 loss in performance with 1.3.x
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2009-04-10 17:10:29

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.

Jeff Squyres
Cisco Systems