Performance Optimization of the HPCG Benchmark on the Sunway TaihuLight Supercomputer.

In this article, we present some key techniques for optimizing HPCG on Sunway TaihuLight and demonstrate how to achieve high performance in memory-bound applications by exploiting specific characteristics of the hardware architecture. In particular, we utilize a block multicoloring approach for parallelization and propose methods such as requirement-based data mapping and customized gather collective to enhance the effective memory bandwidth. Experiments indicate that the optimized HPCG code can sustain 77% of the theoretical memory bandwidth and scale to the full system of more than 10 million cores, with an aggregated performance of 480.8 Tflop/s and a weak scaling efficiency of 87.3%.