The pessimism behind optimistic simulation

Abstract

In this paper we make an analogy between the time that storage must be maintained in an optimistic simulation and the blocking time in a conservative simulation. By exploring this analogy, we design two new Global Virtual Time (GVT) protocols for Time Warp systems. The first protocol is based on null message clock advancement in conservative approaches. Our main contribution is a new protocol inspired by Misra's circulating marker scheme for deadlock recovery. It is simple enough to be implemented in hardware, takes no overhead in the normal path, can be made to work over non-FIFO links, and its overhead can be dynamically tuned based on computational load.