Performance Portable Applications for Hardware Accelerators: Lessons Learned from SPEC ACCEL

The popular and diverse hardware accelerator ecosystem makes apples-to-apples comparisons between platforms rather difficult. SPEC ACCEL tries to offer a yardstick to compare different accelerator hardware and software ecosystems. This paper uses this SPEC benchmark to compare an AMD GPU, an NVIDIA GPU and an Intel Xeon Phi with respect to performance and energy consumption. It also provides observations on the performance portability between the different platforms. Since the SPEC ACCEL Open ACC suite can yet not be run on a Xeon Phi, that suite was ported to OpenMP 4.0 target directives to enable a comparison. The challenges and solutions of this porting of 15 applications are described as well.