A Comparative Study of Conservative and Optimistic Trace-driven Simulations

In this paper, we consider the evaluation of the memory hierarchy of multiprocessor systems via parallel trace-driven simulation. We study two parallel simulation schemes: a conservative one using an algorithm proposed by Lin et al. [10], whose main characteristic is to insert the shared references from every trace in all other traces, and an optimistic one using a Time Warp-like [9] algorithm. We compare, qualitatively and quantitatively, the major causes of overhead and the overall performance of the two methods. In addition, we discuss the trade-offs in terms of implementation and debugging effort and of application to more general architectural simulation. The optimistic scheme is more complex but, in general, has slightly better performance, is more general, and does not require preprocessing. 3 This work was supported in part by NSF Grants CCR-91-01541, CCR-91-23308 and CCR-94-01689 1 Introduction The amount of computational cycles needed to simulate the performance of parall..