Energy Efficient Scientific Computing on FPGAs using OpenCL

An indispensable part of our modern life is scientific computing which is used in large-scale high-performance systems as well as in low-power smart cyber-physical systems. Hence, accelerators for scientific computing need to be fast and energy efficient. Therefore, partial differential equations (PDEs), as an integral component of many scientific computing tasks, require efficient implementation. In this regard, FPGAs are well suited for data-parallel computations as they occur in PDE solvers. However, including FPGAs in the programming flow is not trivial, as hardware description languages (HDLs) have to be exploited, which requires detailed knowledge of the underlying hardware. This issue is tackled by OpenCL, which allows to write standardized code in a C-like fashion, rendering experience with HDLs unnecessary. Yet, hiding the underlying hardware from the developer makes it challenging to implement solvers that exploit the full FPGA potential. Therefore, we propose in this work a comprehensive set of generic and specific optimization techniques for PDE solvers using OpenCL that improve the FPGA performance and energy efficiency by orders of magnitude. Based on these optimizations, our study shows that, despite the high abstraction level of OpenCL, very energy efficient PDE accelerators on the FPGA fabric can be designed, making the FPGA an ideal solution for power-constrained applications.