Reducing null messages overhead through load balancing in conservative distributed simulation systems

Abstract

This paper studies the problem of load balancing for conservative distributed simulations for execution on a multicomputer architecture. The synchronization protocol makes use of Chandy–Misra null messages. We propose a dynamic load balancing algorithm which assumes no compile time knowledge about the workload parameters. It is based upon a process migration mechanism, and the notion of CPU-queue length which indicates the workload at each processor. We examine two variations of the algorithm—referred to as the centralized and multi-level hierarchical methods—and experiment with four simulation workload models to study the scalability of our algorithm. The experiments indicate that our dynamic load balancing schemes significantly reduce the run time of an optimized version of Chandy–Misra null message approach, and decreases by 30–40% the synchronization overhead when compared to the use of a static partitioning algorithm. The results also indicate that the hierarchical version outperforms both the centralized version of the dynamic load balancing algorithm and the static partitioning scheme.