How do I run parallel code?

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That depends on how the code is "parallelized". If it was "multi-threaded" by the compiler (automatic or via compiler directives), it is usually enough to set the environment variable PARALLEL or OMP_NUM_THREADS to the number of threads that should be used.

If it is MPI code, a special parallel runtime environment has to be used. The command there is mprun, which has command-line options that let you tell how many and which processors to use. This command is part of the CRE (Cluster Runtime Environment). CRE involves a good deal of commands that let you submit, cancel and check jobs that use MPI. The settings for this are included in our default setup.