Evaluation of hardware write propagation support for next-generation shared virtual memory clusters
Angelos Bilas, Liviu Iftode, JASWINDER PAL SINGH · 1998
Clusters of symmetric multiprocessors (SMPs), connected by commodity system-area networks (SANs) and interfaces are fast being adopted as platforms for parallel computing. Page-grained shared virtual memory (SVM) is a popular way to support a coherent shared address space programming model on these clusters. Previous research has identified several key bottlenecks in the communication, protocol and application layers of a software SVM system that are not so significant in more mainstream, hardware-coherent multiprocessors. A key question for the communication layer is how much and what kind of hardware support is particularly valuable in improving the performance of such systems. This paper examines a popular form of hardware support---namely, support for automatic, hardware propagation of writes to remote memories---discussing new design issues and evaluating performance in the context of emerging clusters. Since much of the performance difference is due to differences in contention effects in various parts of the system, performance is examined through very detailed simulation, utilizing the deep visibility into the simulated system to analyze the causes of observed effects.