A globally optimized checkpointing scheme for time warp

Abstract

Time warp (TW) protocol executes simulation events without considering event safety, and a rollback mechanism is used to correct out-of-order event execution. For the. simulator to perform the rollback operation, the system state must be checkpointed. Although decreasing the checkpointing frequency reduces the state saving cost, this is done at the risk of escalating the coast forward effort when a large number of executed events are redone. In this article we improve the TW performance by optimizing its recovery cost. Probabilistic model, and combinatorial analysis are used, and logical processes of the TW simulation and their processing elements are assumed to be homogeneous. Given a set of system states, our scheme selects the best combination of checkpointing positions based on the sum of coast forward cost and state saving cost. Our experiments show that the proposed checkpointing, scheme reduces the simulation elapsed time by 35.% compared to saving the system state after each event execution, and by 20% as compared to infrequent approach.