The efficiency of buffer and buffer-less data-flow control schemes for congestion avoidance in Networks on Chip

The design of efficient architectures for communication in on chip multiprocessors system involves many challenges regarding the internal router functions used in Network on Chip (NoC) infrastructure. The on-chip router should be designed to provide per-flit processing with enhanced granularity. In fact, the quality of service experienced at the application level depends on the capabilities of the router to avoid congestion and to ensure efficient data-flow control. Consequently, an enhanced router architecture is needed to achieve the requested QoS.This paper proposes an internal router architecture, for on chip communication, implementing flow-control mechanism for congestion avoidance with QoS consideration. It describes the internal functions of this router for optimal output flit scheduling and its capability to apply per-class service for inbound flows. The paper focuses mainly on the description and performance analysis of two proposed schemes for data flow control that can be used with the proposed router architecture. The results shown in this paper prove that the application of these proposed schemes in NoC achieves an interesting enhancement in the measured end to end QoS. We carried out an extensive comparison of the proposed solutions with the existing schemes published in the literature to show that the proposed solution outperforms these, maintaining an interesting tradeoff with the hardware characteristics when designed with 45 nm integration technology.