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Using XMPI with LAM

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With LAM 6.5 and XMPI 2.2.3b8 (and above), functionality was added to enhance the usability of XMPI. MPI_Comm_set_name() now affects the name displayed in XMPI. The other change is the addition of "buoys" to XMPI. This change requires special functionality provided in LAM, and may result in a program that is not compatible with other MPI implementations.

XMPI now provides the ability to identify points in user applications through the use of "buoys". Buoys are identifiers that are "dropped" to identify that point on the XMPI trace window. For example, the code below:

#include "mpi.h"

int
main(int argc, char **argv)
{
  int rank, size;

  MPI_Init(&argc, &argv);

  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
  MPI_Comm_size(MPI_COMM_WORLD, &size);

  XMPI_Buoy("I'm alive");
  
  MPI_Finalize();
  return 0;
}
will produce the following trace visualization when run on 4 ranks: