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Subject: Re: [OMPI users] How do I run OpenMPI safely on a Nehalem standalone machine?
From: Douglas Guptill (douglas.guptill_at_[hidden])
Date: 2010-05-05 19:54:56

On Wed, May 05, 2010 at 06:08:57PM -0400, Gus Correa wrote:

> If anybody else has Open MPI working with hyperthreading and "sm"
> on a Nehalem box, I would appreciate any information about the
> Linux distro and kernel version being used.

Debian 5 (lenny), Core i7 920, Asus P6T MoBo, 12GB RAM, OpenMPI 1.2.8
(with a custom-built MPI_recv.c and MPI_Send.c, which cut down on the
cpu load caused by the busy wait polling). We have six (6) of these
machines. All configured the same.

uname -a yields:
Linux screm 2.6.26-2-amd64 #1 SMP Thu Feb 11 00:59:32 UTC 2010 x86_64 GNU/Linux

HyperThreading is on.

Applications are -np 2 only:
  mpirun --host localhost,localhost --byslot --mca btl sm,self -np 2 ${BIN}

We normally run (up to) 4 of these jobs on each machine.

Using Intel 11.0.074 and 11.1.0** compilers; have trouble with the
11.1.0** and "-mcmodel=large -shared-intel" builds. Trouble meaning
the numerical results vary strangely. Still working on that problem.

Hope that helps,

P.S. Yes, I know OpenMPI 1.2.8 is old. We have been using it for 2
years with no apparent problems. When I saw comments like "machine
hung" for 1.4.1, and "data loss" for 1.3.x, I put aside thoughts of

  Douglas Guptill                       voice: 902-461-9749
  Research Assistant, LSC 4640          email: douglas.guptill_at_[hidden]
  Oceanography Department               fax:   902-494-3877
  Dalhousie University
  Halifax, NS, B3H 4J1, Canada