
Linux Kernel Power Management 

29 April 2003

Patrick Mochel


Abstract

Power management is the process by which the overall consumption of
power by a computer is limited based on user requirements and
policy. Power management has become a hot topic in the computer world
in recent years, as laptops have become more commonplace and users
have become more conscious of the environmental and financial effects
of limited power resources. 

While there is no such thing as perfect power management, since all
computers must use some amount of power to run, there have been many
advances in system and software architectures to conserve the amount
of power being used. Exploiting these features is key to providing
good system- and device-level power management. 

This paper discusses recent advances in the power management
infrastructure of the Linux kernel that will allow Linux to fully
exploit the power management capabilities of the various platforms
that it runs on. These advances will allow the kernel to provide
equally great power management, using a simple interface, regardless
of the underlying archtitecture. 

This paper covers the two broad areas of power management - System
Power Management (SPM) and Device Power Management (DPM). It describes
the major concepts behind both subjects and describes the new kernel
infrastructure for implement both. It also discusses the mechanism for
implementing hibernation, otherwise known as suspend-to-disk, support
for Linux. 

