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

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