The 179th R-CCS Cafe - part 1

The state-of-the-art topology for modern supercomputers are Folded Clos networks, a.k.a. Fat-Trees. The node count in these massively parallel systems is steadily increasing. This forces an increased path length, which limits gains for latency-sensitive applications. A novel, yet only theoretically investigated, alternative is the low-diameter HyperX. To perform a fair side-by-side comparison between a 3-level Fat-Tree and a 12x8 HyperX, we constructed the world's first 3 Pflop/s supercomputer with these two networks. We show through a variety of benchmarks that the HyperX, together with our novel communication pattern-aware routing, can challenge the performance of traditional Fat-Trees.