Slack-Time Closed-Loop Control System for Multimedia Mobile Devices

Nowadays there is a pervasive utilization of consumer-electronics mobile devices with powerful multimedia capabilities. The suitable management of their power consumption is critical in order to meet the user expectations in terms of battery lifetime. But the reduction of the dynamic-power component of the consumption may sometimes impair the quality of multimedia experience (QoE), which is not always acceptable. This paper proposes a closed-loop control system that can monitor the QoE in the form of the slack time of video decoding tasks and act on the CPU frequency to regulate it. Some results are presented in comparison with dynamic Linux governors which show a suitable behavior in guaranteeing enough QoE, even with power savings of almost 5% and low overhead. This enables its use as an assistant part of dynamic-power savers.