Performance Evaluation of the Multi-language Helios Rotorcraft Simulation Software

This paper describes application of the TAU (Tuning and Analysis Utilities) performance system^reg within Helios, a code being developed for high-fidelity modeling of rotorcraft aero and structural dynamics. TAU provides information about both single processor and parallel scaling performance. Helios consists of multiple modules written in different languages - FORTRAN90, C, and C++ - that are integrated through a high-level, Python-based infrastructure. This loosely-connected implementation has the advantage that each module can be developed separately from one another, but as with any parallel code, a single poor-performing module can hinder the performance and scalability of the suite as a whole. Although Helios is still in the early stages of development, integration with TAU provides a way to investigate performance when the design can be most influenced. The paper discusses the different levels of instrumentation, from run-time at the Python level for a high-level description, to automatic compile-time instrumentation for a more detailed breakdown. In both cases, the instrumentation is automatic, requiring no manual insertion of timers on the part of the developer. We report how these tools were used to diagnose single processor performance and parallel scaling issues.