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Subject: Re: [OMPI devel] Fwd: [OMPI bugs] [Open MPI] #1250: Performance problem on SM
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2008-07-23 11:32:01


On Jul 23, 2008, at 10:37 AM, Terry Dontje wrote:

> This seems to work for me too. What is interesting is my
> experiments have shown that if you run on RH5.1 you don't need to
> set mpi_yield_when_idle to 0.

Yes, this makes sense -- on RHEL5.1, it's a much newer Linux kernel
and PLPA works as expected there. So ODLS uses the values that PLPA
passes back and all is good.

On older Linux kernels, we're effectively returning "not supported"
from paffinity, and therefore ODLS (rightly) assumes that it can't
know anything and puts us into the "oversubscribed" state.

I'm working on a fix.

-- 
Jeff Squyres
Cisco Systems