MPI-2: standards beyond the message-passing model

The MPI (Message-Passing Interface) Standard has been successful in its goal of promoting portable parallel programming for both application writers and library implementors. MPI-I confined itself to the well-known and understood message-passing model, in which a fixed number of processes with separate address spaces communicate only though cooperative operations such as send/receive or collective operations such as broadcast and reduce. In a second round of activity, the MPI Forum has recently concluded work on the MPI-2 Standard, which extends MPI beyond the message-passing programming model in a number of ways, including dynamic process management, one-sided operations, and some shared-memory operations. The message-passing model has also been used in MPI-2 as a model for parallel I/O. This paper describes the salient features of the MPI-2 Standard with special emphasis on the programming model that results from these extensions to the message-passing model.