The roll back chip: hardware support for distributed simulation using time warp

Distributed simulation offers an attractive means of meeting the high computational demands of discrete event simulation programs. The Time Warp mechanism has been proposed to ensure correct sequencing of events in distributed simulation programs without blocking processes unnecessarily. However, the overhead of state saving and rollback in Time Warp is one obstacle that may severely degrade performance. A special purpose hardware component, the rollback chip (RBC), is proposed to manage the state of a processor and provide an efficient rollback mechanism within a node of a parallel computer. The chip may be viewed as a special purpose memory management unit that lies on the data path between processor and memory. The algorithm implemented by the rollback chip is described, as well as extensions to the basic design. Implementation of the chip is briefly discussed. In addition to distributed simulation, the rollback chip may be used in other applications using the Time Warp mechanism, notably distributed database concurrency control.