Analyzing Topology Parameters for Achieving Energy-Efficient k-ary n-cubes

Achieving an optimal performance/energy ratio is a challenge for massively parallel computer architects, and in particular for the interconnection network designers. The k-ary n-cube is one of the most popular topologies used in the largest current supercomputers. In this paper, we present a study that considers two alternatives to build k-ary n-cube topologies taking advantage of the high-radix switches currently available: a topology with more dimensions and one NIC per router, or a topology with less dimensions, link aggregation and several NICs per router. The fact of using link aggregation eases the implementation of simple power consumption reduction techniques. Using a simple power model, we evaluate by trace-driven simulation the impact on energy and performance of several network sizes for both topology proposals. In order to do a fair comparison, we keep fixed the theoretical network bandwidth.