Transparent Incremental State Saving in Time Warp Parallel Discrete Event Simulation

Many systems rely on the ability to rollback (or restore) parts of the system state to undo or recover from undesired or erroneous computations. Examples of such systems include fault tolerant systems with checkpointing, editors with undo capabilities, transaction and data base systems and optimistically synchronized parallel and distributed simulations. An essential part of such systems is the state saving mechanism. It should not only allow efficient state saving, but also support efficient state restoration in case of roll back. Furthermore, it is often a requirement that this mechanism is transparent to the user. In this paper we present a method to implement a transparent incremental state saving mechanism in an optimistically synchronized parallel discrete event simulation system based on the Time Warp mechanism. The usefulness of this approach is demonstrated by simulations of large, detailed, realistic FCA and a DCA-like cellular phone systems.