The Effects of Latency, Occupancy, and Bandwidth in Distributed Shared Memory Multiprocessors
Chris Holt, Mark A. Heinrich, JASWINDER PAL SINGH, Edward E. Rothberg, John LeRoy Hennessy · 1995
Designers of distributed shared memory (DSM) multiprocessors are moving toward the use of commodity parts, not only in the processor and memory subsytem but also in the communication architecture. While the desire to use commodity parts and not perturb the underlying uniprocessor node can compromise the efficiency of the communication architecture, the impact on the end performance of applications is unclear. In this paper we study this performance impact through detailed simulation and analytical modeling, using a range of important applications and computational kernels. We characterize the communication architectures of DSM machines by four parameters, similar to those in the logP model. The l (latency) and o (occupancy of the communication controller in this model) parameters are the keys to performance in these machines, with the g (gap or node-to-network bandwidth) parameter not being a bottleneck in recent and upcoming machines. Conventional wisdom is that latency is the domina...