Appendix B: Converting PVM Applications to MPI

Silicon Graphics has adopted MPI as the message-passing model for the POWER CHALLENGEarray and other Array products, and provides a low-latency, high-bandwidth implementation of MPI for these systems. Programmers are encouraged to write new message-passing applications using MPI, and to port existing applications to MPI when that is feasible.

Many existing message-passing applications use the PVM library, owing to its widespread use for the last five years. In order to support this application base, Silicon Graphics, Inc. also supports PVM for Array systems. However, the design of the MPI interface is such that the performance of the MPI implementation on these systems will always be better than the performance of PVM. To obtain best performance, porting parallel programs from PVM to MPI is recommended.

This appendix covers the following main topics:

• "Differences Between PVM and MPI" gives an overview of the differences that are likely to cause difficulty in porting.

• "Comparing Library Routines" lists the PVM routines and their MPI counterparts, when a counterpart exists.

• "Converting a PVM Program to an MPI Program" covers the tasks involved in porting.

• "Example Programs" shows example conversions.

Differences Between PVM and MPI

Comparing Library Routines

Converting a PVM Program to an MPI Program

Example Programs