Running an Intel® MPI Program

The easiest way to run an MPI program is using the mpirun command:

　　$ mpirun -n <# of processes> ./myprog

This command invokes the mpiexec.hydra command which uses the Hydra Process Manager by default. Use the mpiexec.hydra options on the mpirun command line.

Use the -n option to set the number of MPI processes. If the -n option is not specified, the process manager pulls the host list from a job scheduler, or uses the number of cores on the machine.

By default, the ssh protocol is used for communication between nodes. If you are using rsh instead, use -r rsh option:

　　$ mpirun -r rsh -n <# of processes> ./myprog

For a successful run, configure password-less ssh connections for all nodes. For more details, see the Job Startup Commands topic in Intel® MPI Library Reference Manual for Linux* OS.

If you successfully run your application using the Intel® MPI Library, you can move your application from one cluster to another and use different fabrics between the nodes without re-linking. If you encounter problems, see Debugging and Testing for possible solutions.