A monitoring and adaptive routing mechanism for QoS traffic on mesh NoC architectures

The development of MPSoCs targeting embedded systems with a dynamic workload of applications constitutes an important challenge. The growing number of applications running on these systems produces a considerable utilization of resources, implying a high demand of computation and communication in the different MPSoC parts. The heterogeneity of processing elements brings to the application traffic a dynamic and unpredictable nature, due to the variability on data injection rates. NoCs are the communication infrastructure to be used in such systems, due to its performance, reliability and scalability. Different strategies may be employed to deal with traffic congestion, such as adaptive routing, buffer sizing, and even task migration. The goal of this work is to investigate the use of adaptive routing algorithms, where the path between source and target PEs may be modified due to congestion events. The major part of the state of art proposals have a limited view of NoCs, since each NoC router takes decisions based on few neighbors' congestion status. Such local decision may lead packets to other congested regions, therefore being inefficient. This paper presents a new method, where congestion analysis considers information of all routers in the source-target path. This method relies on a protocol for QoS session establishment, followed by distributed monitoring and re-route to non-congested regions. The set of experiments present results concerning performance and amount of time spent by packets on routers when the proposed method is applied.