(Contributed by William Gropp and Ewing Lusk)
MPI (Message-Passing Interface) is a message-passing standard library interfacethat has developed by a broad group of massively parallel processor (MPP) vendors and users. A partial implementation of the standard as it stood in May 1993 was implemented and run on the SP1.
since then the MPI standard has been completed and multiple versions are available on the SP1. All make efficient use of the high-performance switch, and are comparable to IBM's fastest message-passing library products. A portable version that allows porting from a very large number of machines and workstation networks to the SP1 is described in [7].