Manyfold actors: extending the C++ actor framework to heterogeneous many-core machines using OpenCL

The processing power of modern many core hardware such as graphics processing units (GPUs) or coprocessors is increasingly available for general-purpose computation. The seamless way of actor systems to addresses concurrent and distributed programming makes it an attractive approach to integrate these novel architectures. In this work, we introduce OpenCL-enabled actors to the C++ Actor Framework (CAF). This offers a high level interface for accessing any OpenCL device without leaving the actor paradigm. The new type of actor is integrated into the runtime environment of CAF and gives rise to transparent message passing in distributed systems on heterogeneous hardware. New actors are instantiated by the function spawn_cl, while the runtime environment handles the discovery and setup of OpenCL devices in the background. Our evaluations on a commodity GPU, an Nvidia TESLA, and an Intel PHI reveal the expected linear scaling behavior when offloading larger work items. For sub-second duties, the efficiency of offloading was found to largely differ between devices. Moreover, our findings indicate a negligible overhead over programming the native OpenCL API.