VARIATIONS ON LOW-LEVEL COMMUNICATION BENCHMARKS

The ratio between CPU speed and memory speed has grown in recent pars. Consequently, cache miss penalties have become very expensive in term s of the number of CPU operations that can be performed instead. A sim ilar evolution has occurred with the ratio between communication speed and memory speed. Startup time and communication bandwidth have impro ved significantly, while memory bandwidth has increased more slowly. T his phenomenon calls for a revision of the influence of the memory hie rarchy on communication performance. This article presents a case stud y about the influence of contiguous and noncontiguous data transfers o n communication performance. A benchmark included in the PARKBENCH ben chmark suite (COMMS1) was modified to produce a more detailed picture of the memory access effect on communication, A performance model for message transfer through cache is also presented.