Accelerating Kirchhoff Migration on GPU Using Directives

Accelerators offer the potential to significantly improve the performance of scientific applications when offloading compute intensive portions of programs to the accelerators. However, effectively tapping their full potential is difficult owing to the programmability challenges faced by the users when mapping computation algorithms to the massively parallel architectures such as GPUs.Directive-based programming models offer programmers an option to rapidly create prototype applications by annotating region of code for offloading with hints to the compiler. This is critical to improve the productivity in the production code. In this paper, we study the effectiveness of a high-level directivebased programming model, OpenACC, for parallelizing a seismic migration application called Kirchhoff Migration on GPU architecture. Kirchhoff Migration is a real-world production code in the Oil & Gas industry. Because of its compute intensive property, we focus on the computation part and explore different mechanisms to effectively harness GPU´s computation capabilities and memory hierarchy. We also analyze different loop transformation techniques in different OpenACC compilers and compare their performance differences. Compared toone socket (10 CPU cores) on the experimental platform, one GPU achieved a maximum speedup of 20.54x and 6.72x for interpolation and extrapolation kernel functions.