Optimizations for Efficient Array Redistribution on Distributed Memory Multicomputers

Abstract

Appropriate data distribution has been found to be critical for obtaining good performance on distributed memory multicomputers such as the Thinking Machines CM-5, Intel Paragon, and IBM SP-1/SP-2. It has also been found that some programs need to change their distributions during execution for better performance (redistribution). This work focuses on automatically generating efficient routines for redistribution. We present a new mathematical representation for regular distributions called FALLS and then discuss algorithms for redistribution based on this representation. One of the significant contributions of this work is being able to handle arbitrary source and target processor sets while performing redistribution. Another important contribution is the ability to handle an arbitrary number of dimensions for the array involved in the redistribution in a scalable manner. Our implementation of these techniques is based on the MPI communication library. The results presented show the efficiency and scalability of our redistribution algorithm.