The performance value of shared network caches in clustered multiprocessor workstations

This paper evaluates the benefit of adding a shared cache to the network interface as a means of improving the performance of networked workstations configured as a distributed shared memory multiprocessor. A cache on the network interface offers the potential benefits of retaining evicted processor cache lines, providing implicit prefetching, and increasing intra-cluster sharing. Using simulation, eight parallel scientific applications were used to evaluate the performance impact of a shared network cache. In each case, we examined in detail the means by which processor cache misses were satisfied. For the applications studied, we found that the network cache offers substantial performance benefit when processor caches are too small to hold the application's primary working set, or when network contention limits application performance. The expected benefits of implicit prefetching and increased intra-cluster sharing did not contribute significantly to the performance enhancement of the network cache for most applications. Finally, the advantage afforded by the network cache diminishes as processor cache size increases and network contention decreases.