MPI-SIM: using parallel simulation to evaluate MPI programs

This paper describes the design and implementation of MPI-SIM, a library for the execution driven parallel simulation of MPI programs. MPI-LITE, a portable library that supports multithreaded MPI, is also described. MPI-SIM, built on top of MPI-LITE, can be used to predict the performance of existing MPI programs as a function of architectural characteristics, including number of processors and message communication latencies. The simulation models can be executed sequentially or in parallel. Parallel executions of MPI-SIM models are synchronized using a set of asynchronous conservative protocols. MPI-SIM reduces synchronization overheads by exploiting the communication characteristics of the program it simulates. This paper presents validation and performance results from the use of MPI-SIM to simulate applications from the NAS Parallel Benchmark suite. Using the techniques described here, we are able to reduce the number of synchronizations in the parallel simulation as compared with the synchronous quantum protocol and are able to achieve speedups ranging from 3.2-11.9 in going from sequential to parallel simulation using 16 processors on the IBM SP2.