SQTW: a mechanism for state-dependent parallel simulation. Description and experimental study

We address the problem of efficiently performing parallel discrete-event simulation in the case where event elaboration is independent of other processes' local states. We propose a parallel simulation policy, called State Query Time Warp (SQTW), based on the Time Warp mechanism. We present experiments performed by means of a SQTW-based parallel simulator on a T-800 transputer machine for solving performance models based on state-dependent routing queueing network models. The experiments are used for assessing overheads and efficiency involved by SQTW; results show that high efficiency is achievable, and surprisingly reveal that SQTW is able to globally reduce rollback overheads with respect to corresponding Time Warp simulations.