Today, I attended the first Distinguished Lecture talk of 2008 in the Department of Computer Science at the University of Toronto. The talk was by
Carla Ellis of the Computer Science department at Duke University. Her talk was on energy aware computing. Can computing contribute to energy conservation in non-computer environments? This was the major motivation towards her research. She reviewed how there is computational support for the science of global change for reducing energy demand. We have progressed far with energy management for computing from various levels. First, we have dealt with energy management at the hardware level with low-power circuit design. Second, the operating system has support for energy management such as detecting voltage changes and scaling. Third, there are policies that govern energy management in computing, with popular techniques being caching and prefetching. The operating system can spin the disk down when not in use, and we have energy management schemes for our laptops, like to conserve battery by decreasing the brightness of the display. Fourth, we have software for energy management, with much systems research dealing with this. Carla and her research group have built an energy-centric OS which is nicely called ECOSystem.
When coming up with an energy goal, it is important to know to be aware of the tradeoffs that can occur, like for example, the battery lifetime can be increased however the CPU may be downclocked to run at a lower speed, or there might be a sacrifice in performance. We need to know whether the tradeoffs are justified. In their project called ECOSystem, there is explicit managing of energy use to reach the target battery lifetime. The premise is to fully utilize the battery life within a set timeframe. The scenario that she used was that of a person being able to use the laptop all the way on a coast-to-coast flight across the country, like for example from Halifax to Vancouver. They use a unifying energy concept in ECOSystem which is called currentcy which is equal to current + currency to provide a cost model for energy. Their model is a pay as you go model, ie, you can use currentcy during an epoch. If there is no more currentcy, then there is no more service. Therefore, currentcy needs to be allocated amongst the resources, but care needs to be taken such that no resource hoards all the energy. Therefore, the energy needs to be distributed evenly for the task at hand. As part of the ECOSystem, there is currentcy-aware scheduling to determine which resources get allocated what amount of currentcy and up to how much (cap), as well as buffer management strategies and prefetching (common of all energy-aware computing research).
The second research area Carla described was that of context-aware energy computing in environments, in which at Duke University, there is a smart home with the newest technologies and “green” initiatives. Their problem was to count the number of people that walk through the doorway so that for example, lights could be switched off, if the last person leaves the room, or the thermostat can be adjusted so that it is not too hot in the room (which she mentioned could have been used in the lecture room she was talking in). In fact, she is taking her own research personally by building her own smart house, transferring research and technology into her own house.
The third research project that Carla next talked about was the soil-moisture forestry project in which she is working with biologists to measure soil moisture to determine when to sample and how to sample. Her research group is looking into soil moisture data and developing models to suppress transmission.
She concluded her talk by issuing a challenge to all computer scientists. Any subdiscipline of computer science can find research topics related to energy efficiency (like for example, using energy as a new metric for research), but not necessary having to go heavily into the area. There is need for interdisciplinary research and it is a challenge to do interdisciplinary research. There is a trend to support energy conservation in buildings and transportation systems, which shows the practical applications. She mentioned how collaborative applications can be written for more effective teleconferencing/telecommuting that exploit the energy conservation. She also mentioned that energy-aware applications can take technologies and research from software engineering, machine learning, and systems.
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Carla Ellis,
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