Communication Requirements of Software Distributed Shared Memory Systems

Software Distributed Shared Memory (DSM) systems have been proposed to provide the convenience of shared memory programming on clusters of workstations. Different research groups advocate specific design decisions in their implementations. In this paper we present an experimental comparison of the communication requirements of three different page based systems software DSM systems, CVM, Quarks and Strings. Programs from the SPLASH-2 benchmark suite and some computational kernels are used to evaluate these systems. This paper shows the effect of different design decisions used in each of the DSMs on the same evaluation environment, a cluster of symmetrical multiprocessors. It is seen that systems that allow multiple application threads, like Strings and CVM, require lower number of messages when compared to Quarks. CVM and Quarks use user level threads for implementing the runtime, and it seen that they cannot effectively exploit multiple processors on each node. The Strings DSM uses kernel level threads and shows the best overall performance in a majority of the applications examined.