Exploiting big.LITTLE Batteries for Software Defined Management on Mobile Devices

Battery service time is a critical constraint on the availability and functionality of mobile devices. To address the challenge, we propose CAPMAN, a management framework that jointly optimizes the cooling and active power management in a smartphone, a typical mobile device, equipped with a hybrid battery pack. We establish the framework with three major designs. First, we abstract the correlation among the batteries, devices and software into a finite state machine model, whose state transitions can be triggered by actions like system calls and user activities. Second, we propose a battery scheduling algorithm that determines the more suitable battery for cooling/active power use, with respect to the dynamic software behaviors and their impact on the hardware states, based on Markov decision process (MDP). Third, we design a facility for joint cooling and active power management by coordinating TECs and batteries. With the three major designs, CAPMAN realizes software defined management that schedules heterogeneous batteries and TEC cooling in a timely manner. We prototype CAPMAN on multiple popular smartphones and a PYNQ development board. CAPMAN can achieve 114% longer battery service time under skewed loads; compared to baselines, CAPMAN shows 55% performance gain and 53% less energy use on average