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Subject: Re: [OMPI users] 50% performance reduction due to OpenMPI v 1.3.2 forcing all MPI traffic over Ethernet instead of using Infiniband
From: Jim Kress ORG (jimkress_58_at_[hidden])
Date: 2009-06-23 16:31:22


Ralph,

I did the following:

export OMPI_MCA_mpi_show_mca_params="file,env"

then I checked and found it via the set command as

OMPI_MCA_mpi_show_mca_params=file,env

I then ran my application

./orca hexatriene_TDDFT_get_asa_input_parallel_1.inp >
1.2.8_test_crafted_input_file.out

and got the expected ORCA output in the .out file but nothing at the
command line or in the .out file about mca_params

What did I do wrong?

Jim

On Mon, 2009-06-22 at 19:40 -0600, Ralph Castain wrote:
> Sounds very strange, indeed. You might want to check that your app is
> actually getting the MCA param that you think it is. Try adding:
>
> -mca mpi_show_mca_params file,env
>
> to your cmd line. This will cause rank=0 to output the MCA params it
> thinks were set via the default files and/or environment (including
> cmd line).
>
> Ralph
>
> On Jun 22, 2009, at 6:14 PM, Jim Kress ORG wrote:
>
> > For the app I am using, ORCA (a Quantum Chemistry program), when it
> > was
> > compiled using openMPI 1.2.8 and run under 1.2.8 with the following in
> > the openmpi-mca-params.conf file:
> >
> > btl=self,openib
> >
> > the app ran fine with no traffic over my Ethernet network and all
> > traffic over my Infiniband network.
> >
> > However, now that ORCA has been recompiled with openMPI v1.3.2 and run
> > under 1.3.2 (using the same openmpi-mca-params.conf file), the
> > performance has been reduced by 50% and all the MPI traffic is going
> > over the Ethernet network.
> >
> > As a matter of fact, the openMPI v1.3.2 performance now looks exactly
> > like the performance I get if I use MPICH 1.2.7.
> >
> > Anyone have any ideas:
> >
> > 1) How could this have happened?
> >
> > 2) How can I fix it?
> >
> > a 50% reduction in performance is just not acceptable. Ideas/
> > suggestions would be appreciated.
> >
> > Jim
> >
> > _______________________________________________
> > users mailing list
> > users_at_[hidden]
> > http://www.open-mpi.org/mailman/listinfo.cgi/users
>
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