Valved routing: Efficient flow control in interconnection networks using misrouting

Misrouting deroutes messages away from their destinations in an interconnection network to bypass the congested region, avoid possible deadlock, and improve the network throughput. The deadlock and livelock problems in misrouting have been studied in recent papers. The starvation and performance degradation problems are not fully exploited and existing approaches tend to be complex and ineffective. In this paper, we propose a new misrouting scheme, called valved routing, which solves the performance degradation and starvation problems by controlling the traffic entering into and flowing around in the network. Valved routing applies the concept of permutation in message-passing and attempts to integrate message injection with routing. The result is that valved routing is simple to implement - only two extra handshaking lines are needed to exchange load information between neighboring routers. We will show that valved routing is deadlock and starvation free for a general router model. Simulation results show that valved routing achieves a more than 50% improvement in network throughput when compared with voluntary misrouting