Performance Evaluation of the Quadrics Interconnection Network

In this paper we present an in-depth description of the Quadrics interconnection network (QsNET) and an experimental performance evaluation on a 64-node AlphaServer cluster. We explore several performance dimensions and scaling properties of the network by using a collection of benchmarks, based on different traffic patterns. Experiments with permutation patterns and uniform traffic are conducted to illustrate the basic characteristics of the interconnect under conditions commonly created by parallel scientific applications. Moreover, the behavior of the QsNET under I/O traffic, and the influence of the placement of the I/O servers are analyzed. The effects of using dedicated I/O nodes or shared I/O nodes are also exposed. In addition, we evaluate how background I/O traffic interferes with other parallel applications running concurrently. The experimental results indicate that the QsNET provides excellent performance in most cases, with excellent contention resolution mechanisms. Some important guidelines for applications and I/O servers mapping on large-scale clusters are also given.