CAREER: Maximizing Energy Efficiency with Statistical Performance and Skin Temperature Quality of Service Guarantee for Handheld Platforms

Arizona State University, Scottsdale AZ

Investigators

Abstract

Smartphones reached almost 4 billion world-wide subscriptions in 2015 and have become our daily companion providing both high capacity computing, as well as personalized computing. For smartphones, user satisfaction determines the success or failure for a particular platform. The top ranked factor of user satisfaction is performance, which can be experienced by users through computation performance and battery performance. Therefore, smartphone designs must achieve balance between performance, temperature and energy management in a coordinated manner to maximize user satisfaction. Performance as measured by mobile application execution time has long been assumed to be a deterministic quantity. In reality, execution times vary substantially, depending on the characteristics of data inputs and the varying states of the system. Furthermore, the device surface temperature is a unique constraint for handheld devices. It is tightly coupled with the location of the major heat-generating source within a smartphone. Thus, a smartphone's energy efficiency is intricately related to both performance quality and skin temperature management, making optimization for system energy efficiency a complex task for battery-powered platforms. With the prevalence of portable electronics, the research outcome has a profound impact on the advancement of the relevant research domains and on society. The research agenda is complemented by an education agenda focusing on the design of handheld platforms, such as smartphones and other high-performance wearable electronics. The educational agenda includes (1) new graduate and undergraduate curricula that incorporates processor and handheld temperature and energy management techniques, (2) enhancing computer architecture and mobile computing courses through lab activities on the proposed skin temperature management for mobile devices, (3) mentoring undergraduate and graduate students in research, and (4) attracting and retaining underrepresented groups of students in STEM fields. This research tackles the problem of performance, temperature and energy efficiency co-optimization from the vantage point of managing the hardware resources. It builds on the PI?s prior work in system and hardware architecture by proposing an optimizing user satisfaction (OPUS) framework for holistic management and coordination of performance quality, skin temperature, and energy efficiency for handhelds. Through accurate execution time models, OPUS dynamically adjusts the mobile platforms to meet the different quality of service goals. The research investigates the dynamic voltage-frequency scaling and temperature-aware computation acceleration algorithms, as well as emerging dynamic cooling mechanisms, suitable for handheld platforms. Optimizing for performance, energy efficiency, or temperature is not new, but optimizing devices in the context of smartphone user satisfaction gives rise to a set of opportunities that are non-existent in conventional computing platforms. The findings can serve as foundations for future user satisfaction optimization research for handheld platforms.