Parallel simulation of large-scale parallel applications

Accurate and efficient simulation of large parallel applications can be fac ilitated with the use of direct execution and parallel discrete-event simul ation. This paper describes MPI-SIM, a direct execution-driven parallel sim ulator designed to predict the performance of existing MPI and MPI-IO appli cation. MPI-SIM can be used to predict the performance of these programs as a function of architectural characteristics, including number of processor s, message communication latencies, caching algorithms, and alternative imp lementations of collective I/O operations. Results are presented, which sho w the use of MPI-SIM in performing a scalability study of real-world applic ations. The benchmarks chosen for the study include Sweep3D, one of the ASC I benchmarks, and BTIO, an I/O-intensive benchmark from the NAS Parallel Be nchmark suite. MPI-SIM is shown to accurately and efficiently predict the p erformance of Sweep3D running on an Origin 2000. It is also used to demonst rate the impact of the number of I/O nodes on BTIO's performance.