Networks-on-Chip

Chapter 6

Flow control for fully adaptive routing^†

Abstract

Routing algorithms for cache-coherent networks-on-chip have only limited virtual channels (VCs) at their disposal, which poses challenges for the design of routing algorithms. Existing fully adaptive routing algorithms apply conservative VC reallocation: only empty VCs can be reallocated, which limits performance. We propose two novel flow control designs. First, whole packet forwarding reallocates a nonempty VC if the VC has enough free buffers for an entire packet. Whole packet forwarding does not induce deadlock if the routing algorithm is deadlock-free using conservative VC reallocation. It is an important extension to several deadlock avoidance theories. Second, we extend Duato’s ...