A hybrid display frame buffer architecture for energy efficient display subsystems

Our principal motivation is to reduce the energy consumption of display subsystems in mobile devices by introducing a hybrid frame buffer architecture into the platform. We observed that display contents on a screen are quite static for certain mobile workloads, such as web browsing. As a result, data reading from the display frame is much more frequent than the writing of new data onto the frame buffer, a state we refer to as read dominance. Based on this observation, we propose a hybrid frame buffer architecture that exploits the display contents' read-dominant property to improve the energy efficiency of display subsystems. Specifically, we employ two memory types: DRAM and Phase-Change Memory (PCM), in the display frame buffer to exploit their different read/write energy characteristics. We also present an analysis of the energy efficiency of the hybrid frame buffer based on our display content and energy consumption models. Our evaluation results show that the proposed hybrid frame buffer reduces frame buffer energy consumption by up to 43%, compared to the conventional DRAM-only frame buffer.