In-channel misrouting suppression technique for deflection-routed networks on chip

Abstract

Deflection routing, where port-contentions in routers are resolved by intentionally misrouting some of packets along unwanted directions instead of storing them, has been proposed as a promising approach for improving power and area efficiency of large-scale networks on chip (NoCs). However, at high network load, when packets are misrouted more frequently, the cost and energy benefits of this simple routing scheme are offset by the performance degradation. To address this problem, we propose a technique that uses small in-channel buffers to capture some of deflected packets before they take a misrouting hop. The captured packets are then looped-back to the routers where they suffered deflection and routed again. To improve the efficiency of this in-channel misrouting suppression scheme we also slightly modify the routing function of the deflection router by restricting the choice of productive directions for misrouted packets. Evaluations on synthetic traffic patterns show that the proposed misrouting suppression mechanism yields an improvement of 36.2% in network saturation throughput when implemented into the conventional deflection-routed network.