Operating System Services for Task-Specific Power Management - Novel Approaches to Energy - Aware Embedded Linux

Mobile computing devices like PDAs cell phones or laptops have become anindispensable part of everyday's life. As these systems are battery-poweredand the user expects long operating times energy-aware operation is crucial.Hardware components for mobile devices offer low-power operating modesthat achieve energy savings at the cost of degraded performance or applicationquality e.g. by reducing the CPU speed. This dissertation investigatessoftware-controlled energy management and addresses these two often conflictinggoals: increasing the embedded system's runtime by saving energyand providing sufficient application quality. With a cooperative approach betweenthe operating system and individual applications or the user task-specifictrade-offs between these goals can be made. Prototype implementationsfor embedded Linux are presented and evaluated with energy measurementsproving the feasibility of task-specific power management. This dissertationhas a strong practical focus being a valuable guide for computer scientistsand software engineers both in academia and industry who deal with operatingsystem design and low-power software architectures.