29.0 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.
The features and hardware described in this chapter do not exist on IBM
System z, making this chapter irrelevant for these platforms.
Unlike APM, which was previously used on laptops for
power management only, the hardware information and
configuration tool ACPI is available on all modern computers
(laptops, desktops, and servers). All power management technologies require
suitable hardware and BIOS
routines. Most laptops and many modern desktops and servers meet these
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.
IMPORTANT: Power Management for AMD64 Processors
AMD64 processors with a 64-bit kernel only support ACPI.