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“main” (Installation and Administration) — 2004/6/25 — 13:29 — page 369 — #395

Power Management

Apart from these processes, journaling ﬁle systems, like ReiserFS and

Ext3, write their meta data independently from bdﬂush, which also pre-

vents the hard disk from spinning down. To avoid this, a special kernel ex-

tension has been developed for mobile devices. See /usr/src/linux/

Documentation/laptop-mode.txt for details.

Another important factor is the way active programs behave. For example,

good editors regularly write hidden backups of the currently modiﬁed ﬁle

to the hard disk, causing the disk to wake up. Features like this can be dis-

abled at the expense of data integrity.

In this connection, the mail daemon postﬁx makes use of the variable

POSTFIX_LAPTOP. If this variable is set to yes, postﬁx will access the hard

disk far less frequently. However, this is irrelevant if the interval for kup-

dated was increased.

17.5 powersave

On laptops, the powersave package can be used to control the power sav-

ing function during battery operation. Some of the features of this package

can also be used on normal workstations and servers (suspend, standby,

ACPI button functionality, putting IDE hard disks to sleep).

This package comprises all power management features of your computer.

It supports hardware using ACPI, APM, IDE hard disks, and PowerNow!

or SpeedStep technologies. The functionalities from the packages apmd,

acpid, ospmd, and cpufreqd (now cpuspeed) have been consolidated

in the powersave package. For this reason, daemons from these packages

should not be run together with the powersave daemon.

Even if your system does not have all hardware elements listed above

(APM and ACPI are mutually exclusive), use the powersave daemon for

controlling the power saving function. The daemon automatically detects

any changes in the hardware conﬁguration.

Note

Information about powersave

Apart from this chapter, information about the powersave

package is also available in /usr/share/doc/packages/

powersave/README_POWERSAVE.

Note

369SUSE LINUX Enterprise Server