An Empirical Evaluation of Performance-Memory Trade-offs in Time Warp

We experimentally evaluate the performance of the Time Warp mechanism when only a limited amount of memory is available to the parallel computation. To this end we use an implementation of the cancelback protocol for memory management on a shared memory architecture, viz., KSR to evaluate the performance vs. memory tradeoff. Our implementation of the cancelback protocol supports canceling back more than one memory object when memory has been exhausted (the precise number is referred to as the salvage parameter) and incorporates a non-work conserving processor scheduling technique to prevent starvation. We use several benchmark programs that provide interesting stress cases for evaluating the limited memory behavior. The experiments are extensively monitored to determine the extent to which various factors may affect performance. Several observations are made by analyzing the behavior of Time Warp under limited memory : (i) Depending on the available memory and asymmetry in the workloa..