Unbiased Regional Congestion Aware Selection Function for NoCs

Adaptive routing in Network-on-Chip (NoC) selects paths for packets according to network state to reduce packet latency and balance network load. Existing adaptive routing schemes can degrade network performance due to their dependency on either inadequate or outdated network information. We present an adaptive routing scheme in which a router is provided adequate and timely congestion information of the network. A low-complexity routing selection function that considers regional congestion status is proposed. The selection function is unbiased as it considers the same amount of congestion information on both admissible directions. Proposed selection function achieves 18% lower packet latency than local congestion aware selection under realistic workloads. It also reduces regional congestion aware selection logic area and power overhead by 73% and 35% on an 8×8 mesh network.