Implementation and Analysis of a New Selection Strategy for Adaptive Routing in Networks-on-Chip

Efficient and deadlock-free routing is critical to the performance of networks-on-chip. The effectiveness of any adaptive routing algorithm strongly depends on the underlying selection strategy. When the routing function returns a set of admissible output channels with a cardinality greater than one, a selection function is used to select the output channel to which the packet will be forwarded. In this paper, we present a novel selection strategy that can be coupled with any adaptive routing algorithm. The proposed selection strategy is based on the concept of Neighbors-on-Path, the aim of which is to exploit the situations of indecision occurring when the routing function returns several admissible output channels. The overall objective is to choose the channel that will allow the packet to be routed to its destination along a path that is as free as possible of congested nodes. Performance evaluation is carried out by using a flit-accurate simulator under traffic scenarios generated by both synthetic and real applications. Results obtained show how the proposed selection strategy applied to the Odd-Even routing algorithm yields an improvement in both average delay and saturation point up to 20 percent and 30 percent on average, respectively, with minimal overhead in terms of area occupation. In addition, as a consequence of the improved router efficiency, a positive effect on total energy consumption is also observed under near-congestion packet injection rates.