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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: 2009-04-07 17:16:43


On Tue, Apr 07, 2009 at 02:23:45PM -0600, Ralph Castain wrote:
> It isn't in a file - unless you specify it, OMPI will set it
> automatically based on the number of procs on the node vs. what OMPI
> thinks are the number of available processors. The question is: why
> does OMPI not correctly know the number of processors on your machine?
>
> I don't remember now, but did you send us this info:
>
> http://www.open-mpi.org/community/help/
>
> If not, could you please do so? It would help us track down the problem.
>
> Thanks
> Ralph
>

I've attached config.log.gz from my 1.3.1 build and
the compressed output of

/usr/local/openmpi-1.3.1/bin/ompi_info --all > ompi_info.all

My PATH is

PATH=/home/kargl/bin:/sbin:/usr/sbin:/bin:/usr/bin:/usr/local/bin:\
     /usr/local/libexec:/usr/local/sbin

LD_LIBRARY_PATH is unset, and should be irrelevant because everything
is statically linked.

The command lines are
/usr/local/openmpi-1.3.1/bin/mpicc -o z -O -static GetOpt.c netmpi.c
/usr/local/openmpi-1.3.1/bin/mpiexec -machinefile mf_ompi_2 \
   -mca mpi_yield_when_idle 0 -n 2 ./z
/usr/local/openmpi-1.3.1/bin/mpiexec -machinefile mf_ompi_2 -n 2 ./z

The former gives performance on par with 1.2.9 while the latter is
a factor of 10 slower.

-- 
Steve