On Dec 15, 2011, at 9:09 AM, Joao Amaral wrote:

> Strangely(?), in both my laptop and the cluster, the number of threads from 
> the command
> 
> call MPI_Comm_size ( MPI_COMM_WORLD, p, error )

Did you really mean "threads" there?

Open MPI is process-parallel, meaning that calling COMM_SIZE on a communicator 
will return the number of *processes* in that communicator, not threads.

See the man page for mpirun(1) for how to launch multiple processes in a single 
MPI job.  Quick example:

    mpirun --hostfile your_host_file -np 8 your_mpi_program

where:

your_host_file: a file listing the host names to launch on
8: number of copies of your_mpi_program to launch
your_mpi_program: your compiled executable MPI application

-- 
Jeff Squyres
jsquy...@cisco.com
For corporate legal information go to:
http://www.cisco.com/web/about/doing_business/legal/cri/


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