TOPIC: Howto fine tune power management settings for G3 Powerbooks Using PMUD

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Introduction:
This HOWTO covers the procedure for changing & fine tuning the default power management settings for G3 Powerbooks. The PMUD utility is included with the YellowDog Linux distribution.

Additional information can be obtained at the PMUD Sourceforge site,

http://sourceforge.net/projects/apmud/

Or, by reading the PMUD man page:

man pmud

The instructions found in this HOWTO assume you have root access to the machine & are logged in as such.


1. Verify PMUD Installation & Status:

After a fresh install of YellowDog Linux, you can verify the PMUD daemon is installed & running by issuing the following command:

/etc/rc.d/init.d/pmud status

Which should return something close to the following if the daemon is running:

pmud (pid 1741) is running...

If the daemon is installed, but not running, you will see the following:

pmud is stopped

If you receive any other messages or errors, you should verify the PMUD installation by issuing the following command:

ls /sbin/ /etc/rc.d/init.d/ | grep pmud

Which should return the following if PMUD is installed:

pmud
pmud

If you find that PMUD is not installed, insert your YellowDog Linux installation CD & issue the following commands:

mount /mnt/cdrom rpm -ivh /mnt/cdrom/YellowDog/ppc/pmud-0.10-1b.ppc.rpm

At this point, you should have a copy of the PMUD daemon installed, & you should be able to verify it's status.


2. Specifying Power Management Settings: Power management options are specified in the /etc/sysconfig/power file. Using your favorite text editor, open the file:

vi /etc/sysconfig/power

You will see the following:

PMUD_FLAGS=

You may specify the power options that best suit your needs. (Refer to the PMUD man page for the complete list of daemon switches)

The following example would:
1. Power off the screen on lid close, but *not* put the machine to sleep; 2. Set the critical low battery level to 90 seconds of battery remaining; 3. Put the machine to sleep 15 seconds after reaching the critical battery low level.

PMUD_FLAGS="-k -l 90 -m 15"

After making any changes to the power settings, issue the following commands:

/etc/rc.d/init.d/pmud stop
/etc/rc.d/init.d/pmud start

You may then check the daemon status by issuing:

/etc/rc.d/init.d/pmud status

3. Power Consumption Settings
The PMUD daemon reads the /etc/power/levels file at startup to determine the power consumption rules it must follow. Two numeric values are specified in this file. The first is the battery policy, the second is the AC policy. Valid settings for either rule are:

1 = Minimum power consumption
2 = Medium power consumption
3 = Maximum power consumption

You may set these values to suit your needs. If you find that /etc/power/levels doesn't exist, issue the following command:

cat > /etc/power/levels
1 2
(ctrl+d to exit)

That example would set the battery policy to 1 (minimum consumption) and the AC policy to 2 (minimum consumption).

After making changes to /etc/power/levels, you will need to restart the PMUD daemon:

/etc/rc.d/init.d/pmud stop
/etc/rc.d/init.d/pmud start

You may then check the daemon status by issuing:

/etc/rc.d/init.d/pmud status

This HOWTO was written by William Carty