xBSP: an efficient BSP implementation for cLAN

Virtual Interface Architecture (VIA) is a light-weight protocol for protected user-level zero-copy communication. In spite of the high performance of VIA, the previous MPI implementation for GigaNet's cLAN revealed low communication performance. The main sources of the low performance are the discrepancy of communication model between MPI and VIA and multi-threading overhead. We propose a novel implementation of the Bulk Synchronous Parallel (BSP) programming library for VIA called xBSP for overcoming such problems. To the best of our knowledge, xBSP is the first implementation of the BSP library for VIA. xBSP demonstrates that selecting a proper library is important to exploit the features of light-weight protocols. The intensive use of RDMA operation leads to high performance, close to the native VIA performance with respect to round trip delay and bandwidth. Based on the study of the effects of multithreading, memory registration, and completion policy on performance, we could obtain an efficient BSP implementation for cLAN, which is confirmed by experimental results.