Predictable photonic interconnects using an autonomous channel management and a TDMA-NoC

Enhancing an electrical NoC with a reconfigurable nano-photonic interconnect architecture contributes to mitigate the bandwidth bottleneck typically found in modern systems. The management of such photonic channels, however, complicates the control of the network and deteriorates its predictability. For the autonomous management of the photonic links with full predictability, this work proposes a hybrid architecture, where several distributed hardware agents connected with a TDMA-based electrical NoC with a photonic layer. These agents provide a dynamic (at run-time) configuration infrastructure for the photonic switches; thanks to the bounded delay of the TDMA-NoC, the configuration overhead can be accurately predicted and the quality-of-service guaranteed. Furthermore, the architecture is highly scalable due to the predictable, autonomous, and decentralised administration of the links. This paper reports an architectural evaluation which combines a thorough analysis of the hardware cost at the gate level and a functional validation of the improved predictability; the results confirm the suitability of the approach.