Performance Engineering of GemsFDTD Computational Electromagnetics Solver

Since modern high-performance computer systems consist of many hardware components and software layers, they present severe challenges for application developers who are primarily domain scientists and not experts with continually evolving hardware and system software. Effective tools for performance analysis are therefore decisive when developing performant scalable parallel applications. Such tools must be convenient to employ in the application development process and analysis must be both clear to interpret and yet comprehensive in the level of detail provided. We describe how the Scalasca toolset was applied in engineering the GemsFDTD computational electromagnetics solver, and the dramatic performance and scalability gains thereby achieved.