COMPaS: A Pentium Pro PC-based SMP Cluster and Its Experience

We have built an eight node SMP cluster called COMPaS (Cluster Of Multi-Processor Systems), each node of which is a quadprocessor Pentium Pro PC. We have designed and implemented a remote memory based user-level communication layer which provides lowoverhead and high bandwidth using Myrinet. We designed a hybrid programming model in order to take advantage of locality in each SMP node. Intra-node computations utilize a multi-threaded programming style (Solaris threads) and inter-node programming is based on message passing and remote memory operations. In this paper we report on this hybrid shared memory/distributed memory programming on COMPaS and its preliminary evaluation. The performance of COMPaS is a ected by data size and access patterns, and the proportion of inter-node communication. If the data size is small enough to all t on the cache, parallel e ciency exceeds 1.0 using the hybrid programming model on COMPaS. But the performance is limited by the low memory bus bandwidth of PC-based SMP nodes for some memory intensive workloads.