The Quest for a Zero Overhead Shared Memory Parallel Machine

In this paper we present a new approach to benchmark the performance of shared memory systems. This approach focuses on recognizing how far off is the performance of a given memory system from a realistic ideal parallel machine. We define such a realistic machine model called the z-machine, which accounts for the inherent communication costs in an application by tracking the data flow in the application. The z-machine is incorporated into an execution-driven simulation framework to be used as a reference for benchmarking for different memory systems. The components of the overheads in these memory systems are identified and quantified for four applications. Using the z-machine performance as the standard to strive for we discuss the implications of the performance results and suggest architectural trends to pursue for realizing a zero overhead shared memory machine.