Abstract: OpenACC is a programming standard designed to simplify heterogeneous parallel programming by using directives.Since OpenACC can generate OpenCL and CUDA code,meanwhile running OpenCL on Intel Knight Corner is supported by CAPS HMPP compiler,it is attractive to using OpenACC on hardwares with different underlying micro-architectures.This paper studied how realistic it is to use a single OpenACC source code for a set of hardwares with different underlying micro-architectures.Intel Knight Corner and Nvidia Kepler products are the targets in the exper- iment,since they have the latest architectures and similar peak performance.Meanwhile CAPS OpenACC compiler is used to compile EPCC OpenACC benchmark suite,Stream and MaxFlops of SHOC benchmarks to access the performance.To study the performance portability,roofline model and relative performance model were built by the data of experiments.It shows that at most 82% performance compared with peak performance on Kepler and Knight Corner is achieved by specific benchmarks,but as the rise of arithmetic intensity,the average performance is approximately 10%.And there is a big performance gap between Intel Knight Corner and Nvidia Kepler on several benchmarks.This study confirmed that performance portability of OpenACC is related to the arithmetic intensity and a big performance gap still exsits in specific benchmarks between different hardware platforms.

Key words: OpenACC,Performance portabilty,High performance computing