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