Near-Optimal Rendezvous Protocols for RDMA-Enabled Clusters

Optimizing Message Passing Interface (MPI) point-to-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 RDMA-enabled 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.