Throughput Models of Interconnection Networks: The Good, the Bad, and the Ugly

Throughput performance, an important metric for interconnection networks, is often quantified by the aggregate throughput for a set of representative traffic patterns. A number of models have been developed to estimate the aggregate throughput for a given traffic pattern on an interconnection network. Since all of the models predict the same property of interconnection networks, ideally, they should give similar performance results or at least follow the same performance trend. In this work, we examine four commonly used interconnect throughput models and identify the cases when all models show similar trends, when different models yield different trends, and when different models produce contradictory results. Our study reveals important properties of the models and demonstrates the subtle differences among them, which are important for an interconnect designer/researcher to understand, in order to properly select a throughput model in the process of interconnect evaluation.