Event reconstruction in time warp

Abstract

In optimistic simulations, checkpointing techniques are often used to reduce the overhead caused by state saving. In this paper, we propose event reconstruction as a technique with which to reduce the overhead caused by event saving, and compare its memory consumption and execution time to the results obtained by dynamic checkpointing. As the name implies, event reconstruction reconstructs input events and anti-events from the differences between adjacent states, and does not save input events in the event queue. For simulations with fine event granularity and small state size, such as the logic simulation of VLSI circuitry, event reconstruction can yield an improvement in execution time as well as a significant reduction in memory utilization when compared to dynamic checkpointing. Moreover, this technique facilitates load migration because only the state queue needs to be moved from one processor to another.