Runtime Adaptive Circuit Switching and Flow Priority in NoC-Based MPSoCs

With the significant increase in the number of processing elements in NoC-based MPSoCs, communication becomes, increasingly, a critical resource for performance gains and quality-of-service (QoS) guarantees. The main gap observed in the NoC-based MPSoCs literature is the runtime adaptive techniques to meet QoS. In the absence of such techniques, the system user must statically define, for example, the scheduling policy, communication priorities, and the communication switching mode of applications. The goal of this paper is to investigate the runtime adaptation of the NoC resources, according to the QoS requirements of each application running in the MPSoC. This paper adopts an NoC architecture with duplicated physical channels, adaptive routing, support to flow priorities and simultaneous packet and circuit switching. The monitoring and adaptation management is performed at the operating system level, ensuring QoS to the monitored applications. The QoS acts in the flow priority and the switching mode. Monitoring and QoS adaptation were implemented in software, resulting in flexibility to apply the techniques to other platforms or include other adaptive techniques, as task migration or DVFS. Applications with latency and throughput deadlines run concurrently with best-effort applications. Results with synthetic and real application reduced in average 60% the latency violations, ensuring smaller jitter and throughput. The execution time of applications is not penalized applying the proposed QoS adaptation methods.