A <i>Q</i> -Learning-Based Display Energy Optimization Scheme for Android Systems

Mobile devices have gained immense popularity in recent years and have become an integral part of people’s daily lives. This surge in usage presents new challenges for energy conservation, particularly concerning the screens of mobile phones. Not only are screens being used for longer durations, but also their adjustment needs to be dynamically conducted during runtime. Existing approaches for display energy optimization mainly focus on the display content while disregarding user interactions. This limitation prevents the full exploitation of opportunities to reduce screen energy consumption during runtime. Detection-based display energy optimization approaches incorporate user interactions to some extent. However, these approaches require additional hardware and offer relatively coarse-grained control. To address these challenges, we propose QLEO, a Q-learning-based runtime display energy optimization scheme for Android systems. QLEO takes both the display and user interaction features into account. By dynamically classifying the user state into active and idle states based on these features, we enable adaptive screen brightness adjustments according to the user’s current state. We formulate display energy optimization as a constrained dynamic optimization problem and propose an integrated Q-learning model to effectively solve it. QLEO is designed as a module within the hardware abstraction layer, capable of obtaining display and user interaction features from the upper Android framework, and directly controlling the screen brightness through the underlying Linux kernel. We have implemented QLEO on real hardware and released the source code for public access. The experimental results demonstrate that QLEO achieves significant energy reduction without compromising the user experience.