Energy-Efficient Scheduling for Portable Computers as Bi-Criteria Optimization Problem

Many of today’s portable computers are not inferior to the computing power of a desktop computer. The main problem of portable computers is short duration of activity of the device in standalone mode, while ensuring the quality of service, i.e., subjective user satisfaction. There is no single way of measuring subjective user satisfaction as the current quality of the service requirements conflicts with the requirements to ensure uptime portable computers. Power consumption model of the portable computer is presented as 3-level power graph. The developed model of the multitasking system’s scheduling in a portable computer battery life is based on the assumption that the problem under consideration belongs to the soft real-time subject. Synthesis of schedules multitasking system in a portable computer battery life is carried out by solving the bi-criteria optimization problem with the release of the Pareto-optimal solutions. These criteria includes minimum penalty for the decline in the quality of service and maximum battery life with the current profile of power consumption. For experimental investigation of the power consumption PCMark-7 and Microsoft Joulemeter were used. As a result of experiments it is found that during operation on portable computers minimum and maximum energy levels differ by more than 2 times. A time transition to a low or high voltage processor, respectively, can lead to a twofold increase in battery life. The latter is, of course, the most optimistic estimate, since an increase in battery life portable computers only 10–20 % will give the user quite noticeable and necessary advantages.