Event-based DVFS control in GALS-ANoC MPSoCs

Many Processor Systems on Chip (MPSoCs) have become tremendously complex systems and more sensitive to variabilities with technology scaling. Globally Asynchronous Locally Synchronous (GALS) designs alleviate such problems by having multiple clocks, each one being distributed on a small area of the chip. Also, power constraints are of great interest for mobile platforms powered by battery and power management techniques, mainly based on Dynamic Voltage and Frequency Scaling (DVFS) algorithms, are hence required. Whereas a closed-loop feedback has been shown as an efficient solution in the monoprocessor case, the present paper is dedicated to a multiprocessor architecture where a decentralized global controller manages the different voltage/frequency domains into a chip. The main innovation of the proposal is the use of event-based methods, where the control updates are event driven. Thus, the communicating instants are decided w.r.t. the dynamics of the system to control. The proposed framework is tested in simulation. It notably highlights a strong reduction in the sampling and communication instants and, consequently, in the energy consumption since the communication consumes a lot in such a MPSoC configuration.