Interconnection networks are a critical resource for large supercomputers. The dragonfly topology, which provides a low network diameter and large bisection bandwidth, is being explored as a promising option for building multi-Petaflop/s and Exaflop/s systems. Unlike the extensively studied torus networks, the best choices of message routing and job placement strategies for the dragonfly topology are not well understood. This paper aims at analyzing the behavior of a machine built using a dragonfly network for various routing strategies, job placement policies, and application communication patterns. Our study is based on a novel model that predicts traffic on individual links for direct, indirect, and adaptive routing strategies. We analyze results for individual communication patterns and some common parallel job workloads. The predictions presented in this paper are for a 100+ Petaflop/s prototype machine with 92,160 highradix routers and 8.8 million cores. The RRR scheme is similar to the RRN scheme, but allocates routers instead of individual nodes to a job in a round robin manner. Kamil et al. [21] have defined topological degree of communication (TDC) of a processor as the number of its communication partners. They study a large set of important applications and show that the TDC of common applications vary from as low as 4 to as large as 255. In order to span a similar range of TDC and study a representative set of common communication patterns [6], [7] , the patterns listed in Table I have been used. Each of the pattern is described in more detail as we analyze prediction results for it in Section V.
We have also studied various routing choices for different communication patterns and parallel workloads on the dragonfly topology REF .
Maximizing throughput on a dragonfly network
SC14: International Conference for High Performance Computing, Networking, Storage and Analysis
SC14: International Conference for High Performance Computing, Networking, Storage and Analysis
Computer Science