PI PU PL QoSU QoSI Tolerable Unusable -ESU ESI EST Quality-of-Service (QoS) Energy Savings (ES) Performance Degradation ▸ Need a systematic way of understanding and QoS-energy trade-offs. To that end we advocate eQoS to strike a balance between user satisfaction and energy reduction ▸ Develop the event-based scheduling (EBS) mechanism that exploits the fundamental event-driven execution pattern of mobile applications to achieve better eQoS ▸ User interactivity and human perceptibility are important because it has economic ramifications and impacts user device choice, as well as end-user satisfaction Heterogeneous Hardware Event Queue H3 … H2 … H1 Dispatch <Core, Freq> PI, PU Detector QoS Monitor Model Constructor Recalibrate Event-Based Scheduler Event Info Models onkeyup=“H1 () {…}” keyup onchange=“H2 () {…}” change Event execution feedback onclick=“H3 () {…}” click