GRACE: Cross-Layer Adaptation for Multimedia Quality and Battery Energy

Mobile devices primarily processing multimedia data need to support multimedia quality with limited battery energy. To address this challenging problem, researchers have introduced adaptation into multiple system layers, ranging from hardware to applications. Given these adaptive layers, a new challenge is how to coordinate them to fully exploit the adaptation benefits. This paper presents a novel cross-layer adaptation framework, called GRACE, that coordinates the adaptation of the CPU hardware, OS scheduling, and multimedia quality based on user’s preferences. To balance the benefits and overhead of cross-layer adaptation, GRACE takes a hierarchical approach: It globally adapts all three layers to large system changes, such as application entry or exit, and internally adapts individual layers to small changes in the processed multimedia data. We have implemented GRACE on an HP laptop with the adaptive Athlon CPU, Linux-based OS, and video codecs. Our experimental results show that compared to schemes that adapt only some layers or adapt only to large changes, GRACE reduces the laptop’s energy consumption by 1.4% to 31.4% while providing better or same video quality.