Louhi User's Guide, the 2nd Edition > Program development > Using MPI > Writing MPI programs
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Writing MPI programs

This subsection briefly describes writing MPI programs on Louhi.

The MPI implementation on Louhi is based on MPICH-2. MPI programs can be written with Fortran, C or C++.

MPI-2 Support

The MPI version on Louhi is MPI 2.0 compliant, excluding the dynamic process features and thread safety. Most importantly, MPI-I/O is available and is recommended for parallelizing the I/O.

More precisely, the following commands are not supported:

  • MPI_CLOSE_PORT and MPI_OPEN_PORT
  • MPI_COMM_ACCEPT
  • MPI_COMM_CONNECT and MPI_COMM_DISCONNECT
  • MPI_COMM_SPAWN and MPI_COMM_SPAWN_MULTIPLE
  • MPI_COMM_GET_ATTR - with attribute MPI_UNIVERSE_SIZE
  • MPI_COMM_GET_PARENT
  • MPI_LOOKUP_NAME
  • MPI_PUBLISH_NAME and MPI_UNPUBLISH_NAME
The MPI_LONG_DOUBLE data type is not supported.


Include Files

Instead of

include 'mpif.h'

to introduce MPI definitions Fortran programmers can use the corresponding module:

use mpi

For C/C++ use

#include <mpi.h>

C++ programmers should, however, note that there is a name conflict between stdio.h and the C++ binding. This can be avoided by including mpi.h before stdio.h or the iostream routine.

Further Information

For more information see man intro_mpi.