Scalability Study of the KSR-1

There has been concern in the architectural community regarding the scalability of shared memory parallel architectures owing to the potential for large latencies for remote memory accesses. KSR-1 is a re cently introduced commercial shared memory parallel architecture, and the scalability of KSR-1 is the focus of this research. Our key conclusions are as follows: The communication network of KSR-1 is fairly re silient in supporting simultaneous remote memory ac cesses from several processors. The multiple communi cation paths realized through this pipelining help in the efficient implementation of tournament-style barrier synchronization algorithms. The architectural features of KSR-1 such as the poststore and prefetch are useful for boosting the performance of parallel applications. The network does saturate when there are simultane ous remote memory accesses from a fully populated (32 node) ring.