Million-Core-Scalable Simulation of the Elastic Migration Algorithm on Sunway TaihuLight Supercomputer

Migration algorithm is one of the most essential methods in seismic application to image the underground geology, and to help scientists and researchers in geophysics exploration better understand the earth system. However, due to the desire in migration algorithm for covering lager region and acquiring better resolution, many tough challenges have to be tackled for current state-of-the-art computing systems. This work optimized and scaled the elastic migration algorithm onto the Sunway TaihuLight supercomputer, one of the most powerful systems of the world. Targeting at the major process, the reverse time migration (RTM) algorithm, a set of algorithmic, process-level, and thread-level optimizations is proposed, to significantly improve the performance (up to 163× speedup in time-to-solution) on Sunway CPU. Our design is successfully scaled to over two million cores (2,662,400 cores in total) on the Sunway TaihuLight supercomputer, with nearly ideal weak-scaling efficiency. The largest run is able to achieve a sustainable performance of processing over 859 billion cells per second.