Software cost analysis of GPU-accelerated aeroacoustics simulations in C++ with openACC

Abstract

Aeroacoustics simulations leverage the tremendous computational power of today’s supercomputers, e.g., to predict the noise emissions of airplanes. The emergence of GPUs that are usable through directive-based programming models like OpenACC promises a costefficient solution for flow-induced noise simulations with respect to hardware expenditure and development time. However, OpenACC’s capabilities for real-world C++ codes have been scarcely investigated so far and software costs are rarely evaluated and modeled for this kind of highperformance projects. In this paper, we present our OpenACC parallelization of ZFS, an aeroacoustics simulation framework written in C++, and its early performance results. From our implementation work, we derive common pitfalls and lessons-learned for real-world C++ codes using OpenACC. Furthermore, we borrow software cost estimation techniques from software engineering to evaluate the development efforts needed in a directive-based HPC environment. We discuss applicability and challenges of the popular COCOMO II model applied to the parallelization of ZFS.