Analysis of bounded time warp and comparison with YAWNS

Abstract

This article studies an analytic model of parallel discrete-event simulation, comparing the YAWNS conservative synchronization protocol with Bounded Time Warp. The assumed simulation problem is a heavily loaded queuing network where the probability of an idle server is closed to zero. We model workload and job routing in standard ways, then develop and validate methods for computing approximated performance measures as a function of the degree of optimism allowed, overhead costs of state-saving, rollback, and barrier synchronization, and workload aggregation. We find that Bounded Time Warp is superior when the number of servers per physical processor is low (i.e., sparse load), but that aggregating workload improves YAWNS relative performance.