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From: Michael (mklus_at_[hidden])
Date: 2007-04-17 16:30:52


To maintain compatibility with a major HPC center I upgraded(?) from
OpenMPI 1.1.4 to OpenMPI 1.2 on my local cluster.

In testing on my local cluster, 13 dual-Opteron Linux boxes with dual
gigabit ethernet, I discovered that my program runs slower using
OpenMPI 1.2 then OpenMPI 1.1.4 (780.3 versus 402.4 seconds with 3
processes--tested twice to be certain).

This particular version of my program was designed to minimize the
amount of communications and the only MPI calls that get used a lot
are MPI_SEND and MPI_RECV with MPI_PACKED data (so MPI_PACK and
MPI_UNPACK also get used a lot).

Was there a known problem with OpenMPI 1.2 (r14027) and ethernet
communication that got fixed later?

The same executable run at the major center seems fine, but they have
Myrinet.

Michael