Running the collect Command for MPI

The collect command can be used to trace and profile MPI applications.

To collect data, use the following syntax:

collect [collect-arguments] mpirun [mpirun-arguments] -- program-name [program-arguments]

For example, the following command runs MPI tracing and profiling on each of the 16 MPI processes, storing the data in a single MPI experiment:

collect -M CT8.2 mpirun -np 16 -- a.out 3 5

The initial collect process reformats the mpirun command to specify running the collect command with appropriate arguments on each of the individual MPI processes.

The ‐‐ argument immediately before the program_name is required for MPI profiling. If you do not include the ‐‐ argument, the collect command displays an error message and no experiment is collected.

The technique of using the mpirun command to spawn explicit collect commands on the MPI processes is no longer supported for collecting MPI trace data. You can still use this technique for collecting other types of data.