One Quadrillion Triangles Queried on One Million Processors

We update our prior 2017 Graph Challenge submission [7] on large scale triangle counting in distributed memory by demonstrating scaling and validation on trillion-edge scale-free graphs. We incorporate recent distributed communication optimizations developed for irregular communication workloads [1], and demonstrate scaling up to 1.5 million cores of IBM BG/Q Sequoia at LLNL. We validate our implementation using nonstochastic Kronecker graph generation where ground-truth local and global triangle counts are known, and model our Kronecker graph inputs after the Graph500 [5] R-MAT inputs. To our knowledge, our results are the largest triangle count experiments on synthetic scale-free graphs to date.