Implementation of XcalableMP Device Acceleration Extention with OpenCL

Due to their outstanding computational performance, many acceleration devices, such as GPUs, the Cell Broadband Engine (Cell/B.E.), and multi-core computing are attracting a lot of attention in the field of high-performance computing. Although there are many programming models and languages de-signed for programming accelerators, such as CUDA, AMD Accelerated Parallel Processing (AMD APP), and OpenCL, these models remain difficult and complex. Furthermore, when programming for accelerator-enhanced clusters, we have to use an inter-node programming interface, such as MPI to coordinate the nodes. In order to address these problems and reduce complexity, an extension to XcalableMP (XMP), a PGAS language, for use on accelerator-enhanced clusters, called XcalableMP Device Acceleration Extension (XMP-dev), is proposed. In XMP-dev, a global distributed data is mapped onto distributed memory of each accelerator, and a fragment of codes can be of-floaded to execute in a set of accelerators. It eliminates the complex programming between nodes and accelerators and between nodes. In this paper, we present an implementation of the XMP-dev runtime library with the OpenCL APIs, while the previous implementation targets CUDA-only. Since OpenCL is a standardized interface supported for various kinds of accelerators, it improves the portability of XMP-dev and reduces the cost of development. In the result of performance evaluation, we show that the OpenCL implementation of XMP-dev can generate portable programs that can run on not only NVIDIA GPU-enhanced clusters but also various accelerator-enhanced clusters.