Centralized Adaptive Routing for NoCs

As the number of applications and programmable units in CMPs and MPSoCs increases, the Network-on-Chip (NoC) encounters diverse and time dependent traffic loads. This trend motivates the introduction of NoC load-balanced, adaptive routing mechanisms that achieve higher throughput as compared with traditional oblivious routing schemes that are perceived better suited for hardware implementations. However, an efficient adaptive routing scheme should base its decisions on the global state of the system rather than on local or regional congestion signals as is common in current adaptive routing schemes. In this paper we introduce a novel paradigm of NoC centralized adaptive routing, and a specific design for mesh topology. Our scheme continuously monitors the global traffic load in the network and modifies the routing of packets to improve load balancing accordingly. In our specific mesh-based design, XY or YX routes are adaptively selected for each source-destination pair. We show that while our implementation is scalable and lightweight in hardware costs, it outperforms distributed adaptive routing schemes in terms of load balancing and throughput.