Maximally Adaptive, Deadlock-Free Routing in Spidergon-Donut Network for Large Multicore NOCs

With increasing number of cores in modern processors, an efficient network on a chip (NOC) is the key to next generation processors. Of the many NOC architectures being proposed, the Spider on network has gained popularity due to its low cost and high performance, and has been implemented in commercial processors. Recently, an improved version of this network termed as the Spider on-Donut (SD) network that extends the Spider on network in a second dimension was developed. The SD network results in lower diameter than a 2-D mesh and thus it is a good candidate for future NOC implementations. This paper presents a new routing algorithm for the SD network that is deadlock free and maximally adaptive. By employing our deadlock free algorithm on one of the virtual channels, maximal flexibility can be achieved in routing. We compute the flexibility provided by our deadlock free routing and show that it results in balanced traffic in the network without causing hotspots.