Wall-clock based synchronization: A parallel simulation technology for cluster systems

Abstract

A common practice for reducing synchronization overheads in parallel simulation of a large-scale cluster is to relax synchronization with lengthened synchronous steps. However, as a side effect, simulation accuracy degrades considerably. This paper proposes a novel mechanism that keeps the running speeds of different nodes consistent by synchronizing logical clocks with the wall clock periodically within each lax step. Because speed deviations of nodes are the main source of time causality errors, through aligning speeds our mechanism only causes modest precision loss while achieving a close performance to lax synchronization. The experimental results show that it improves the performance by 2 to 11 times relative to the baseline barrier synchronization with a high accuracy (e.g. 99% in most cases). Compared to the recently proposed adaptive mechanism, it also achieves nearly 30% performance improvement.