Valved routing: efficient flow control for adaptive nonminimal routing in interconnection networks

Adaptive nonminimal routing (or misrouting) may move messages away from their destinations to temporarily cope with the dynamic load in an interconnection network. In most cases, misrouting is more powerful and flexible than minimal routing, especially under nonuniform load distribution. However, to take advantage of its misrouting, we have to avoid deadlock, livelock, and starvation in the network and to maintain the network performance across all levels of loading. In this paper, we propose a new flow control scheme for misrouting, called valved routing. Valved routing controls message injection and transmission through logical valves associated with the router ports. Designing routers using valved routing requires a proper choice of design parameters. We will discuss how to find the range of feasible design parameters. Issues in implementing routers using valved routing will also be addressed. We have conducted extensive simulations to compare the performance of routers with and without valved routing. Our simulation results show that valved routing has promising performance advantages, at light as well as heavy network load. Compared with the voluntary misrouting, valved routing performs better in network throughput without sacrificing the latency