Scalable communication performance prediction using auto-generated pseudo MPI event trace

For the co-design of HPC systems and applications, it is important to study how application performance is affected by the characteristics of the future systems, not just on a computation node but also for the parallel processing including inter-node communications. Trace-driven network simulators have been widely used because of its simplicity. However, they require the trace files corresponding to the simulated system size. Therefore, if a future system is larger than a current system, we can not adopt the trace files directly; that is, it is difficult to simulate a system larger than the current system. In order to address the scaling problem in the trace-driven network simulation, we have proposed a method called SCAlable Mpi Profiler (SCAMP). The SCAMP method runs an application on a current system, obtains MPI-event trace files, copies and edits the real trace files to create a large amount of pseudo MPI-event trace files for a future system, and finally drives a network simulator by inputting the pseudo MPI-event trace files. We also implemented a pseudo MPI-event trace file generator based on the analysis of LLVM's intermediate representations. We aim to easily obtain a first-order approximation of the communication performances for various network configurations and applications. In this paper, we describe the SCAMP system design and implementation as well as several performance evaluation results.