Design space exploration of the dragonfly topology

Abstract

We investigate possible options of creating a Dragonfly topology capable of accommodating a specified number of end-points. We first observe that any Dragonfly topology can be described with two main parameters, imbalance and density, dictating the distribution of routers in groups, and the inter-group connectivity, respectively. We then introduce an algorithm that generates a dragonfly topology by taking the desired number of end-points and these two parameters as input. We calculate a variety of metrics on the generated topologies resulting from a large set of parameter combinations. Based on these metrics, we isolate the subset of topologies that present the best economical and performance trade-off. We conclude by summarizing guidelines for Dragonfly topology design and dimensioning.