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Subject: Re: [OMPI devel] Fwd: [OMPI bugs] [Open MPI] #1250: Performance problem on SM
From: Terry Dontje (Terry.Dontje_at_[hidden])
Date: 2008-07-23 11:48:23


Jeff Squyres wrote:
> 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.
>
Ok, so I thought I saw slow down with Solaris. Not sure it is the same
thing (wouldn't think so) but I'll test this out soon.

--td