MPIExtensions

MPI Extensions

At times developers want to expose non-standard, optional interfaces to users. These interfaces may represent MPI interfaces to be presented to the MPI Forum for standardization. This page describes how a developer would go about introducing a new interface to an Open MPI branch.

For non-standard interfaces, it is strongly suggested that functions are prefixed with OMPI_ instead of MPI_

Directory Structure

branch/ompi/include/mpi.h
branch/ompi/include/mpi-ext.h <auto-generated by autogen.sh and configure>

<MPI standard interfaces>
branch/ompi/mpi/c/
           /mpi/cxx/
           /mpi/f77/
           /mpi/f90/

<OMPI extension interfaces>
branch/ompi/mpiext/
           /mpiext/example/
           /mpiext/example/mpiext*example*c.h
           /mpiext/example/configure.m4
           /mpiext/example/configure.params
           /mpiext/example/Makefile.am
           /mpiext/example/c/
           /mpiext/example/c/progress.c

autogen.sh gathers a list of available extensions in branch/ompi/mpiext. configure then chooses the headers from the enabled extensions and includes them in branch/ompi/include/mpi-ext.h

To create a new extension copy the example directory to whatever you want to identify your extension as (e.g., magic).

shell$ cd ompi/mpiext/
shell$ cp -R example magic

Edit all of the files as need.

Building

In order to build your extension you must explicitly enable it at configure time:

./configure --enable-mpi-ext=magic

If you have more than one extension that you wish to build you can pass them as comma separated values to this configure option:

./configure --enable-mpi-ext=magic,example

Installing

Headers for the extensions will be installed into:

$prefix/include/openmpi/ompi/mpiext/example/mpiext*example*c.h

However programs need only include the base header file, which is linked in properly by the wrapper compilers:

#include <mpi-ext.h>