Reinforcement learning based self-adaptive voltage-swing adjustment of 2.5D I/Os for many-core microprocessor and memory communication

A reinforcement learning based I/O management is developed for energy-efficient communication between many-core microprocessor and memory. Instead of transmitting data under a fixed large voltage-swing, an online reinforcement Q-learning algorithm is developed to perform a self-adaptive voltage-swing control of 2.5D through-silicon interposer (TSI) I/O circuits. Such a voltage-swing adjustment is formulated as a Markov decision process (MDP) problem solved by model-free reinforcement learning under constraints of both power budget and bit-error-rate (BER). Experimental results show that the adaptive 2.5D TSI I/Os designed in 65nm CMOS can achieve an average of 12.5mw I/O power, 4GHz bandwidth and 3.125pJ/bit energy efficiency for one channel under 10^-6 BER, which has 18.89% power saving and 15.11% improvement of energy efficiency on average.