Portability and Performance of Nuclear Reactor Simulations on Many-Core Architectures
Ronald O. Rahaman, David Medina, Amanda L. Lund, John Robert Tramm, Tim Warburton, Andrew R. Siegel · 2015
High-fidelity simulation of a full scale nuclear reactor core is a computational challenge that has yet to be met but is predicted to be achievable on exascale-class supercomputers through established hardware-specific programming models (such as OpenMP and CUDA). Recently-developed, hardware-agnostic programming models offer opportunities to express multi-threaded parallelism in a portable fashion and allow a single, more-unified code base to run on many divergent high-performance computing architectures. Though the benefits of portability are clear, questions remain as to what practical performance tradeoffs apply to real world applications. In the present study, we port two existing proxy applications that represent key algorithms in nuclear reactor simulations to the hardware-agnostic language of OCCA. Performance and efficiency of the OCCA ports are compared to the native OpenMP versions on CPU and CUDA versions on GPU architectures. This study attempts to quantify tradeoffs between performance and portability of real world applications, specifically on exascale-class simulations for nuclear industry, using newer programming models.