Reducing Diff Overhead in Software DSM Systems using RDMA Operations in

Software DSM systems do not perform well because of the combined effects of increase in communication, slow networks and the large overhead associated with processing the coherence protocol. Modern interconnects like Myrinet, Quadrics and InfiniBand offer reliable, low latency (around 5.0 ¡ s point-to-point), and high-bandwidth (upto 10.0 Gbps in 4X InfiniBand). These networks also support efficient memory- based communication primitives like RDMA-Read and RDMA-Write. These supports can be leveraged to effectively reduce overhead in a software DSM system. In this paper, we explore techniques for reducing the diff overhead. These techniques are employed in a protocol called PIPE, which uses RDMA-Write. Application level evaluation shows a maximum improvement of upto 35 % in parallel speedup. Keywords: DSM Systems, Cache coherency protocol, InfiniBand, System Area Network