Quantifying the effects of communication optimizations

Using a specially constructed machine independent communication optimizer that allows control over optimization selection, we quantify the performance benefit of three well known communication optimizations: redundant communication removal, communication combination, and communication pipelining. The numbers are shown relative to the base performance of benchmark programs using the standard communication optimization of message vectorization. The effects on the number of calls to communication routines, both static and dynamic, are tabulated. We consider a variety of communication primitives including those found in Intel's NX library, PVM and the T3D's SHMEM library. The results show substantial improvement, with two combinations of optimizations being most effective.