Smoothed Particle Hydrodynamics Simulations on Multi-GPU Systems

We present a multi-GPU version of GPUSPH, a CUDA implementation of fluid-dynamics models based on the Smoothed Particle Hydrodynamics (SPH) numerical method. SPH is a well-known lagrangian model to simulate fluid flows, it exposes a high degree of parallelism and has already been successfully ported to GPU. We extend the GPU-based simulator to run simulations on multiple GPUs simultaneously, to obtain a gain in speed and overcome the memory limitations of using a single device. The computational domain is spatially split with minimal overlapping and shared volume slices are updated at every iteration of the simulation. Data transfers are asynchronous with computations, thus completely covering the overhead introduced by slice exchange. The obtained speedup factor differs from the ideal one by a small cost function linear in the number of devices, and it is possible to run simulations with a higher number of particles than would fit on a single device.