Evaluating and optimizing OpenCL kernels for high performance computing with FPGAs.

We evaluate the power and performance of the Rodinia benchmark suite using the Altera SDK for OpenCL targeting a Stratix V FPGA against a modern CPU and GPU. We study multiple OpenCL kernels per benchmark, ranging from direct ports of the original GPU implementations to loop-pipelined kernels specifically optimized for FPGAs. Based on our results, we find that even though OpenCL is functionally portable across devices, direct ports of GPU-optimized code do not perform well compared to kernels optimized with FPGA-specific techniques such as sliding windows. However, by exploiting FPGA-specific optimizations, it is possible to achieve up to 3.4x better power efficiency using an Altera Stratix V FPGA in comparison to an NVIDIA K20c GPU, and better run time and power efficiency in comparison to CPU. We also present preliminary results for Arria 10, which, due to hardened FPUs, exhibits noticeably better performance compared to Stratix V in floating-point-intensive benchmarks.