A hybrid CPU/GPU implementation of computationally intensive particle simulations using OpenCL

Particle simulations are popular methods in computational science in areas, such as biology, chemistry, or astrophysics, in which the interaction of particles plays a major role. Efficient implementations of particle simulations often exploit a separation of computations by a cutoff radius. The pairwise interactions between particles are then computed only within the cutoff radius while interactions beyond the cutoff radius might be neglected or computed approximately. Thus, the efficient implementation of the calculations within the cutoff radius can be crucial for an overall efficiency. In this article, we study these computationally intensive inner cutoff radius calculations and propose a portable parallel implementation on a hybrid CPU/GPU architecture. Especially, we have chosen particle methods from the ScaFaCoS library and have implemented a parallel version of the cutoff-based algorithm in OpenCL. Performance results are shown for two different solvers of the ScaFaCoS library. The influences of the particle distribution and the utilized hardware are investigated.