MPI-2 is a significant extension of the MPI-1 standard. Unlike the MPI-1 standard, where complete implementations of the entire standard were available when the standard was released, complete implementations of all of MPI-2 have been slow in coming. As of June 2003, few complete implementations of MPI-2 exist for Beowulf clusters. Most MPI implementations include the MPI-IO routines, in large part because of the ROMIO implementation of these routines, and at least some of the RMA routines (typically the active-target operations
MPI_Put and
MPI_Get , along with
MPI_Win_fence ). Progress continues in both the completeness and performance of MPI-2 implementations, and we expect more full MPI-2 implementations to appear by the end of 2003. One of these is the MPICH2 implementation of MPI.