Near-optimal Rendezvous Protocols for RDMA-enabled Clusters

Abstract—Optimizing Message Passing Interface (MPI) pointto-point communication for large messages is of paramount importance since most communications in MPI applications are performed by such operations. Remote Direct Memory Access (RDMA) allows one-sided data transfer and provides great flexibility in the design of efficient communication protocols for large messages. However, achieving high performance on RDMAenabled clusters is still challenging due to the complexity both in communication protocols and in protocol invocation scenarios. In this work, we investigate a profile-driven compiled-assisted protocol customization approach for efficient communication on RDMA-enabled clusters. We analyze existing protocols and show that they are not ideal in many situations. By leveraging the RDMA capability, we develop a set of protocols that can provide near-optimal performance for all protocol invocation scenarios, which allows protocol customization to achieve near-optimal performance when the appropriate protocol is used for each communication. Finally, we evaluate the potential benefits of protocol customization using micro-benchmarks and application benchmarks. The results demonstrate that the proposed protocols can out-perform traditional rendezvous protocols to a large degree in many situations and that protocol customization can significantly improve MPI communication performance. I