Low-cost congestion management in networks-on-chip using edge and in-network traffic throttling

Abstract

Implementing cost effective congestion control within the Network-on-Chip (NoC) is a major design challenge. Whenever congestion awareness and/or mitigation is desired, architects typically rely on the use of adaptive routing algorithms, which aim to (intelligently) balance the traffic load throughout the NoC. Nevertheless, the hardware cost incurred by such solutions is quite considerable, since it entails the collection/propagation of traffic-related information and the provisioning of deadlock freedom guarantees. In this paper, we explore the potential of simultaneous edge and in-network traffic throttling, as a low-cost alternative to adaptive routing techniques. Without any reliance on adaptivity by the routing algorithm, combined throttling is demonstrated to yield better (in most cases) throughput improvements than state-of-the-art adaptive routing algorithms, but at a significantly lower cost.