Adaptive computation offloading for energy conservation on battery-powered systems

This paper considers the problem of extending the battery lifetime for a portable computer by off loading its computation to a server. Depending on the inputs, computation time for different instances of a program can vary significantly and they are often difficult to predict. Different from previous studies on computation off loading, our approach does not require estimating the computation time before the execution. We execute the program initially on the portable client with a timeout. If the computation is not completed after the timeout, it is off loaded to the server. We first set the timeout to be the minimum computation time that can benefit from off loading. This method is proved to be 2- competitive. We further consider collecting online statistics of the computation time and find the statistically optimal timeout. Finally, we provide guidelines to construct programs with computation off loading. Experiments show that our methods can save up to 17% more energy than existing approaches.