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We're pleased to announce that we've installed a new version of the OpenMPI parallel computing framework. This new version (1.5.5) will be available alongside existing versions.

This new version includes explicit support for LoadLeveler (the scheduler used on Pan), as well as MPI 2 with spawning functionality.

At present, we have not made 1.5.5 the system default; we've left the default at 1.4.3 for the sake of compatibility with previously built applications.

To switch to OpenMPI 1.5.5, you should to complete the following steps:

  1. Run the program "mpi-selector-menu" at your command prompt, and, when prompted, select the option for openmpi_gcc-1.5.5, for "user" (as opposed to "system").
  2. Log out and log back in.

Please note that applications built against other versions of MPI will need to be recompiled against OpenMPI 1.5.5, otherwise OpenMPI 1.5.5 will not run them correctly.

Also, in LoadLeveler job files, only if using OpenMPI 1.5.5:

  • The job_type directive should be set to "MPICH" instead of "parallel"
  • Your executable must still be run through mpirun, but mpirun will no longer require the "-hostfile ${LOADL_HOSTFILE}" command-line option to mpirun