Experiences in managing energy with ECOSystem

Mobile devices are becoming increasingly popular, from laptops, PDAs, and cell phones to emerging platforms such as wireless sensor networks. Available battery energy has become a critical mobile-system resource. A mobile device\´s usefulness is often limited not by its hardware\´s raw speed but by its battery\´s energy. Energy consumption is a major systems-design challenge. We designed our ECOSystem (Energy-Centric Operating System) prototype to manage energy consumption at the OS level, complementing existing power-management techniques, such as DVS and application adaptation. It\´s based on the ideas that energy management should be a system-wide effort, that we should explicitly recognize energy as a resource, and that we should unify energy management across the system. Even managing one hardware device might require coordination with other system components. Without unified management, application-level energy-saving efforts might not result in reduced energy consumption. ECOSystem incorporates the "currentcy model", which lets the operating system manage energy as a first-class resource. It can also express complex energy-related goals and behaviors, leading to more effective, unified management policies.