Parallel execution of radix sort program using fine-grain communication

The report presents empirical results of fine-grain communication on the 80-processor EM-X distributed-memory multiprocessor. EM-X has hardware support for low latency, high throughput fine-grain communication-this hardware support includes packet generation integrated into the instruction execution pipeline for single-cycle communication overhead, direct memory access for remote references, and rapid context switching for latency tolerance. The authors study the fine-grain communication performance of integer radix sort, a code with irregular communication, on EM-X, and compare it to the Fujitsu AP1000+ and the Cray Server CS6400. The experimental results indicate that EM-X achieves high throughput and low overhead for fine-grain communication. Whereas EM-X's communication performance scales perfectly as one increases the number of processors, other coarse-grain message-passing machines exhibit fluctuation and performance degradation for larger configurations due to network contention.