Fast Triangle Counting on the GPU

Triangle counting in a graph is a building block for clustering coefficients which is a widely used social network analytic for finding key players in a network based on their local connectivity. In this paper we show the first scalable GPU implementation for triangle counting. Our approach uses a new list intersection algorithm called Intersect Path (named after the Merge Path algorithm). This algorithm has two levels of parallelism. The first level partitions the vertices to the streaming multiprocessors on the GPU. The second level is responsible for parallelizing the work across the GPU's streaming processors and utilizing different block sizes. For testing purposes, we used graphs taken from the DIMACS 10 Graph Challenge. Our experiments were conducted on NVIDIA's K40 GPU. Our GPU triangle counting implementation achieves speedups in the range of $9X-32X$ over a CPU sequential implementation.