PhaseNoC: TDM scheduling at the virtual-channel level for efficient network traffic isolation

The efficiency of modern Networks-on-Chip (NoC) is no longer judged solely by their physical scalability, but also by their ability to deliver high performance, Quality-of-Service (QoS), and flow isolation at the minimum possible cost. Although traditional architectures supporting Virtual Channels (VC) offer the resources for flow partitioning and isolation, an adversarial workload can still interfere and degrade the performance of other workloads that are active in a different set of VCs. In this paper, we present PhaseNoC, a truly non-interfering VC-based architecture that adopts Time-Division Multiplexing (TDM) at the VC level. Distinct flows, or application domains, mapped to disjoint sets of VCs are isolated, both inside the router's pipeline and at the network level. Any latency overhead is minimized by appropriate scheduling of flows in separate phases of operation, irrespective of the chosen topology. The resulting design yields significant reductions in the area/delay cost of the network. Experimental results corroborate that - with lower cost than state-of-the-art NoC architectures, and with minimum latency overhead - we remove any flow interference and allow for efficient network traffic isolation.