Power Management; Power Saving Functions - Novell LINUX ENTERPRISE DESKTOP 10 SP2 - DEPLOYMENT GUIDE 08-05-2008 Deployment Manual

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Power Management

Power management is especially important on laptop computers, but is also useful on
other systems. Two technologies are available: APM (advanced power management)
and ACPI (advanced configuration and power interface). In addition to these, it is also
possible to control CPU frequency scaling to save power or decrease noise. These options
can be configured manually or using a special YaST module.
Power management is especially important on laptop computers, but is also useful on
other systems. ACPI (advanced configuration and power interface) is available on all
modern computers (laptops, desktops, and servers). Power management technologies
require suitable hardware and BIOS routines. Most laptops and many modern desktops
and servers meet these requirements. It is also possible to control CPU frequency scaling
to save power or decrease noise.
APM had been used in many older computers. Because APM largely consists of a
function set implemented in the BIOS, the level of APM support may vary depending
on the hardware. This is even more true of ACPI, which is even more complex. For
this reason, it is virtually impossible to recommend one over the other. Simply test the
various procedures on your hardware then select the technology that is best supported.

28.1 Power Saving Functions

Power saving functions are not only significant for the mobile use of laptops, but also
for desktop systems. The main functions and their use in the power management systems
APM and ACPI are:
Power Management 537