OpenMPI will do this on its own.  As shared memory in its mind is preferable to tcp.  We can measure the difference here on the same kind of system (Sun x4600).   If you want to force omitting tcp (should not be needed)  run like this:

mpirun --mca btl ^tcp -np 8 ./a.out

Brock Palen
Center for Advanced Computing
brockp@umich.edu
(734)936-1985

On Apr 25, 2007, at 12:54 PM, Borenstein, Bernard S wrote:

We just got a 8 cpu machine with 64GB of memory.  I've been told it would be advantageous to run MPI codes with shared memory and not use TCP sockets

for this new machine.

How do I do this with OPENMPI.

Thanx,

Bernie Borenstein
The Boeing Company


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