Comparing Ethernet and Myrinet for MPI communication

This paper compares the performance of Myrinet and Eth-ernet as a communication substrate for MPI libraries. MPI library implementations for Myrinet utilize user-level com-munication protocols to provide low latency and high band-width MPI messaging. In contrast, MPI library impleme-nations for Ethernet utilize the operating system network protocol stack, leading to higher message latency and lower message bandwidth. However, on the NAS benchmarks, GM messaging over Myrinet only achieves 5 % higher applica-tion performance than TCP messaging over Ethernet. Fur-thermore, efficient TCP messaging implmentations improve communication latency tolerance, which closes the perfor-mance gap between Myrinet and Ethernet to about 0.5% on the NAS benchmarks. This shows that commodity net-working, if used efficiently, can be a viable alternative to specialized networking for high-performance message pass-ing. 1