A restriction of the elastic time algorithm

A restricted version of elastic time algorithm (ETA), known as restricted elastic time algorithm (RETA), used in parallel discrete event simulation, was discussed. The error potential (EP) value was calculated using state information associated with a restricted set of predecessors of the LP. The potential of RETA in reducing the completion time of the parallel simulation application was demonstrated by using the results of an empirical study on a stress case simulation model

A Restriction of the Elastic Time Algorithm

1 Introduction A parallel discrete event simulator consists of a set of logical processes (LPs), each one modeling a specific portion of the simulated system, which are essentially discrete event simulators having their own simulation clock, their own state variables and their own event list [3]. The execution of a simulation event at an LP usually modifies the LP state and possibly schedules new events to be executed at later simulation time. The scheduling of events among distinct LPs takes place through the exchange of messages carrying the content and the simulation time, namely timestamp, of the event. The central problem of parallel discrete event simulation is synchronization, which must ensure the sequence of event executions at any LP satisfies some correctness criterion, typically timestamp ordering. To solve the synchronization problem many algorithms have been proposed, differing from each other by the strategy for simulating the events. In the conservative strategy an LP executes an event only after determining the event execution will not result in any timestamp order violation. In the optimistic strategy, the LPs execute events aggressively without the guarantee of no timestamp order violation. When real violations are detected, a rollback mechanism is used to recover the state of the simulation application to a correct value. As compared to the conservative strategy, the optimistic one allows the exploitation of parallelism anytime it is possible for violations to occur but they do not