Optimistic-Conservative Synchronization in Distributed Factory Simulation

Distributed simulation is attractive for modeling complicated manufacturing systems having many tools and products, such as a semiconductor wafer fabrication line. However, conservative synchronization approaches can introduce excessive overhead in execution, and result in little parallelism, which can eliminate the speedup promised by distributed simulation. Our experiences in building a distributed simulation model for 300 mm wafer fab using the High Level Architecture (HLA) shows that using model specific information in a novel adaptation of conservative synchronization can achieve very significant reduction in model execution time. This paper defines the time-chop problem for which this adaptation is effective, and formally develops our optimistic-conservative synchronization scheme