Parallel optimization of method of characteristics based on Sunway Bluelight II supercomputer

With the development of nuclear energy technology, reactor physical calculations have higher requirements for calculation accuracy and speed, and it has become an inevitable trend to use high-performance computers for reactor simulation calculations. The method of characteristics (MOC) is currently recognized as the preferred method for simulating neutron transport in the nuclear reactor core. Based on the architecture of Sunway many-core processor and Sunway Bluelight II supercomputer, this paper proposes a fine grained and universal two-level parallelization, including thread-level parallelization and process-level parallelization. In the thread-level parallelization, the methods such as job pipeline optimization, load balancing across CPEs, and I/O optimization are proposed for acceleration. In the process-level parallelization, a mapping method from software to hardware is proposed. This method can make full use of the hardware of Sunway supercomputers and improve the computing efficiency and data transmission efficiency. For the first time, the OpenMOC program is transplanted and parallelly optimized on the Sunway supercomputers, which enriched the application ecology of Sunway supercomputers. Compared with the original program, the two-level parallelization can achieve up to 18.6x speedup. Moreover, our parallelization is capable to run on more than 3750 processes of Sunway Bluelight II supercomputer with good strong and weak scalability.