Abstract
In this paper we discuss and compare three different causality inconsistency tracking mechanisms in support of preemptive rollback in optimistic parallel simulation on myrinet clusters. These mechanisms exhibit different communication/ processing overhead and also different effectiveness in revealing causality inconsistency of the currently executed simulation event. By the results of an empirical study on a classical simulation benchmark we have found some trade-offs between these mechanisms, pointing out indications of application contexts for which each mechanism is expected to be well tailored.