Integrated Energy Control for Hard Real-Time Networks-on-Chip

While Networks-on-Chip (NoCs) are the prevalent solution to provide a scalable interconnect for the complex multiprocessing architectures, their associated energy consumptions have immensely increased. Specifically, hard real-time Networks-on-chip must manifest limited energy consumption as reliability issues in such a shared resource jeopardize the whole system safety. In this paper, we propose a safe and efficient approach that allows global and online energy management under temporal guarantees, i.e., all deadlines of critical functions are met. The approach introduces a control-layer to save energy on the NoC data layer through multiple Power-Aware Network Controllers (PANCs). We explore through PANCs the potential efficiency of integrating multiple energy-savings schemes in the face of the diversity of energy dissipation sources. To safely apply the PANCs in hard real-time systems while meeting the deadlines, a formal worst-case timing analysis of the additional latency induced by the control layer is provided. Experimental results demonstrate the diversity of NoC energy-savings under different combinations of energy-savings schemes. Also, the scalability of the approach is provided, inducing small area overhead.