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Yu David Liu

Typed Energy-Aware Programming

In this talk, I will bridge two largely disjoint areas of research -- type system design and green computing -- and show how classic ideas in typed language design may help promote energy efficiency of software systems and ultimately lead to applications "green by design." First, I will introduce Energy Types, a type system to reason about energy management. Despite the popular perception that energy and power can only be described in joules and watts, real-world energy management is often based on discrete phases and modes, where a phase characterizes a distinct pattern of program workload, and a mode represents an energy state the program is expected to execute in. A key insight of Energy Types is that both phases and modes can be captured as types, and reasoned about by a region-based type system effectively. Energy Types brings energy-conscious programmers into energy optimization, leading to a flavor of proactive energy-aware programming. In the second part of the talk, I will show how mixed static and dynamic typing can combine programmer knowledge and program dynamic characteristics into a unified framework for energy optimization. The mixed type system is capable of capturing highly dynamic energy behaviors, such as scenarios when energy consumption is state-dependent or configuration-dependent, and connecting them with the static type system to preserve the ability for principled reasoning. The two type systems have been built into two Java-like programming languages, ET and Ent, and their impact on energy-aware programming has been evaluated on the platforms of laptops, Android phones, and an emerging platform, Raspberry Pi.

David Liu is an Associate Professor from State University of New York (SUNY) at Binghamton. His research interests include energy-aware language systems, data-intensive software systems, type systems, and software engineering. He is a recipient of the US National Science Foundation CAREER Award and the Google Faculty Research Award. David received his Ph.D. from the Johns Hopkins University in 2007.