Energy-aware task and interrupt management in linux

As multi-core and SMP systems become more gener-ally available, energy management needs in LinuxTM have also become more complex. Energy management in Linux was primarily designed for interactive sys-tems where relatively simple inactivity based strategies worked effectively for most cases. Modern enterprise class hardware needs a more complex power manage-ment strategy to save energy with the least impact on the performance of enterprise workloads. Traditionally, the Linux kernel for servers has been optimized for through-put and not power efficiency. This paper discusses the behaviour of the current task management subsystem (scheduler and loadbalancer) on a multi-core SMP system and its effectiveness in sav-ing energy consumption under several situations (idle, moderate load). It then describes several techniques such as timer migration, task wakeup biasing and related heuristics for reducing energy consumption. The pa-per also looks at possible methods to mitigate interrupts for energy savings during different workloads and con-cludes by discussing some results of these new strate-gies.