Towards a thread-based parallel direct execution simulator

Parallel direct execution simulation is an important tool for performance and scalability analysis of large message passing parallel programs executing on top of a virtual computer. However, detailed simulation of message-passing codes requires a great deal of computation. We are therefore interested in pursuing implementation techniques which can decrease this cost. One idea is to implement the application virtual processes as lightweight threads rather than traditional Unix processes, reducing both on-processor communication costs and context-switching costs. In this paper we describe an initial implementation of a thread-based parallel direct execution simulator. We discuss the advantages of such an approach and present preliminary results that indicate a significant improvement over the process-based approach.