Transitioning HPC software to exascale heterogeneous computing

An increasing portion of the top supercomputers in the world, including Blue Waters, have heterogeneous CPUGPU computational units. As we move towards exascale, we can expect even more pervasive deployment of heterogeneous computational units. While a handful of science teams can already use heterogeneous computational units in their production applications, there is still significant room for the growing use. This paper presents the current state and projected path for transitioning software into this new paradigm. We first summarize the currently practical languages such as OpenCL, OpenACC, and C++AMP, in increasing levels of productivity, highlighting their recent advancements in supporting performance portability and maintainability. We will then give a brief overview of some emerging programming systems such as TANGRAM and Troilet that are designed to further enhance developer productivity for heterogeneous computing.