Distributed Dynamic Rate Adaptation on a Network on Chip with Traffic Distortion

摘要

A NoC-based system subject to real-time constraints requires hard bounds on end-to-end data transfer latencies. Regulating the channel injection rates solves the problem by suppressing link congestion and router queue saturation, provided that the channel rates guarantee fairness in the data distribution. We propose a distributed algorithm for the computation of a channel rate vector solution, suitable for runtime execution on the system. The algorithm takes into account the capacity constraints on every link, but also fulfills the distortion constraints. It leads to a near-optimal solution in a few iterations, with less than 10% of vector distance from the optimal solution. The algorithm is valid for software implementation on manycore systems and applicable to any Network-On-Chip based system. Our hardware implementation is distributed into the network infrastructure and converges in around 500 clock cycles on a 4x4 network configuration.