Astrophysical Particle Simulations with Custom GPU Clusters

We present our new parallel GPU clusters in Beijing and Heidelberg and demonstrate the nearly optimal speedup and performance for parallel direct astrophysical N-body simulations with up to six million bodies. We reach about 1/3 of the peak performance for a real application code. The clusters are used to simulate dense star clusters with many binaries and galactic nuclei with supermassive black holes, in which correlations between distant particles cannot be neglected.