Recently, augmented reality technologies are debuting to the mainstream markets. Currently, smartphones are still the dominant computing platform for providing mobile augmented reality (MAR) experience to users. Nevertheless, MAR on smartphones faces some key challenges as the rich functionalities increase concerns including battery power drain and thermal dissipation. This paper takes the first step to understand the characteristics of MAR apps from the system and architecture perspectives. We observe that MAR apps exhibit much higher Thread-level Parallelism (TLP) and have a potential to better exploit the big.LITTLE architecture. We further build Multi-comPonent Power and Thermal Analysis Tool (MPPTAT) on Android mobile platform to break down the power consumption and thermal dissipation into hardware components, threads, and phases. Power characterization shows that MAR apps exhibit higher energy consumption compared to other popular mobile non-MAR apps, mainly contributed by the camera. Thread level breakdown shows that the major CPU power consumption is MediaServer, which controls the camera to capture and process multimedia information on smartphones. We also investigate the impact of DVFS, and results indicate that current MAR apps' implementations are mostly CPU intensive and the mobile GPU is not well exploited yet. Moreover, thermal characterization shows that compared to the non-MAR apps, the frequent usage of the camera not only increases the temperature of the camera module but also dissipates the heat to other layers, which directly affect user experience. We believe that our work reveals insights for software and hardware designers to fine-tune augmented reality workloads on mobile platforms.
