An evaluation of the Myrinet/GM2 two-port networks

It is important to systematically assess the features and performance of the new interconnects for high performance clusters. This work presents the performance of the two-port Myrinet networks at the GM2 and MPI layers using a complete set of microbenchmarks. We also present the communication characteristics and the performance of the NAS multi-zone benchmarks and SMG2000 application under the MPI and MPI-OpenMP programming paradigms. We found that the host overhead is very small in our cluster, and the Myrinet is sensitive to the buffer reuse patterns. Our applications achieved a better performance for MPI than the mixed-mode. All the applications studied use only nonblocking communications, thus are able to overlap their communications with the computations. Our experiments show that the two-port communication at the GM and MPI levels (except for the RDMA read, and overlap) outperforms the one-port communication for the bandwidth. However, this did not translate into a considerable improvement at least for our applications.