Difference between revisions of "Power Management"

Revision as of 12:26, 23 December 2010

Configuring Hardware - Power Management

If you have a laptop, you will probably want to make a few measures to extend your battery life, such as throttling down your CPU, dimming your LCD backlight, and other things. In this case you will want to make sure the laptop USE flag is set in your /etc/make.conf. If you have a dell laptop, you will also want to add the dell USE flag. Chances are you have already built some of the packages that accept these USE flags, so you may want to rebuild all affected packages on your system.

$ sudo emerge -avDN world

If it hasn't been installed already, you'll want to install the acpi (Advanced Configuration and Power Interface) daemon.

$ sudo emerge -av apcid

Once the package is emerged, we'll start the apci daemon and add it to startup.

$ sudo /etc/init.d/acpid start
$ sudo rc-update add acpid default

The Gentoo power management guide suggests you create a battery runlevel to manage your system while running on battery mode. The drawback to this is having to manage multiple runlevels, and having to add new services to both runlevels. Thankfully, power management can be done fairly easily using the default script provided.

@@ Line 8: / Line 8: @@
   '''$''' sudo /etc/init.d/acpid start
   '''$''' sudo rc-update add acpid default
-The next we'll create a "battery" runlevel for your system.
+The Gentoo power management guide suggests you create a battery runlevel to manage your system while running on battery mode. The drawback to this is having to manage multiple runlevels, and having to add new services to both runlevels. Thankfully, power management can be done fairly easily using the default script provided.
- '''$''' cd /etc/runlevels
+=== /etc/acpi/default.sh ===
- '''$''' sudo cp -a default battery
-This action creates a copy of the default runlevel called battery. ''From now on, whenever you add a service to the default runlevel, if you want it to start up when you are running only on your battery, you will need to add it to the battery runlevel as well.'' The next step will be to create a script that can intercept from the acpid whether or not your system is running on batteries and be able to switch to the appropriate runlevel. This script was blatantly stolen from the gentoo handbook.
- '''$''' sudo mkdir /etc/acpi/actions
- '''$''' sudo nano -w /etc/acpi/actions/pmg_switch_runlevel.sh
-=== /etc/acpi/actions/pmg_switch_runlevel.sh ===
- #!/bin/bash
- # BEGIN configuration
- RUNLEVEL_AC="default"
- RUNLEVEL_BATTERY="battery"
- # END configuration
- if [ ! -d "/etc/runlevels/${RUNLEVEL_AC}" ]
- then
-     logger "${0}: Runlevel ${RUNLEVEL_AC} does not exist. Aborting."
-     exit 1
- fi
- if [ ! -d "/etc/runlevels/${RUNLEVEL_BATTERY}" ]
- then
-     logger "${0}: Runlevel ${RUNLEVEL_BATTERY} does not exist. Aborting."
-     exit 1
- fi
- if on_ac_power
- then
-     if [[ "$(</var/lib/init.d/softlevel)" != "${RUNLEVEL_AC}" ]]
-     then
-         logger "Switching to ${RUNLEVEL_AC} runlevel"
-          /sbin/rc ${RUNLEVEL_AC}
-     fi
- elif [[ "$(</var/lib/init.d/softlevel)" != "${RUNLEVEL_BATTERY}" ]]
- then
-     logger "Switching to ${RUNLEVEL_BATTERY} runlevel"
-     /sbin/rc ${RUNLEVEL_BATTERY}
- fi
-We'll also need to make this script executable.
- '''$''' chmod 755 /etc/acpi/actions/pmg_switch_runlevel.sh
-Next we will need to determine what events are thrown when you unplug or plug in your AC adapter.
- '''$''' sudo tail -f /var/log/messages | grep "ACPI event"
-You should see something like this:
- Dec  7 18:10:30 moonbase3 logger: ACPI event unhandled: ac_adapter AC0 00000080 00000000
- Dec  7 18:10:30 moonbase3 logger: ACPI event unhandled: processor CPU0 00000081 00000000
- Dec  7 18:10:31 moonbase3 logger: ACPI event unhandled: processor CPU1 00000081 00000000
- Dec  7 18:10:31 moonbase3 logger: ACPI event unhandled: processor CPU2 00000081 00000000
- Dec  7 18:10:31 moonbase3 logger: ACPI event unhandled: processor CPU3 00000081 00000000
- Dec  7 18:10:31 moonbase3 logger: ACPI event unhandled: battery BAT0 00000080 00000001
- Dec  7 18:10:33 moonbase3 logger: ACPI event unhandled: ac_adapter AC0 00000080 00000001
- Dec  7 18:10:33 moonbase3 logger: ACPI event unhandled: processor CPU0 00000081 00000000
- Dec  7 18:10:33 moonbase3 logger: ACPI event unhandled: processor CPU1 00000081 00000000
- Dec  7 18:10:33 moonbase3 logger: ACPI event unhandled: processor CPU2 00000081 00000000
- Dec  7 18:10:34 moonbase3 logger: ACPI event unhandled: processor CPU3 00000081 00000000
- Dec  7 18:10:34 moonbase3 logger: ACPI event unhandled: battery BAT0 00000080 00000001
-Press ''ctrl-c'' to end the output. What we're interested in is the info for the AC adapter and battery. We can see in the output above that events for the AC adapter are called ac_adapter, and battery events are called, well, battery. We'll create two files in ''/etc/acpi/actions/'' to intercept the events.
- '''$''' sudo nano -w /etc/acpi/actions/pmg_ac_adapter
-Add the following from the gentoo handbook:
- # replace "ac_adapter" below with the event generated on your laptop
- # For example, ac_adapter.* will match ac_adapter AC 00000080 00000000
- event=ac_adapter.*
- action=/etc/acpi/actions/pmg_switch_runlevel.sh %e
-Do the same for the battery.
- '''$''' sudo nano -w /etc/acpi/actions/pmg_battery
-Add the following from the gentoo handbook:
- # replace "battery" below with the event generated on your laptop
- # For example, battery.* will match battery BAT0 00000080 00000001
- event=battery.*
- action=/etc/acpi/actions/pmg_switch_runlevel.sh %e
-We'll need to restart the daemon for the changes to take effect. To test whether or not the changes actually worked, unplug and plug in the AC adapter. Next we'll check the log to see if it worked. It didn't. fuck

Difference between revisions of "Power Management"

Revision as of 12:26, 23 December 2010

Configuring Hardware - Power Management

/etc/acpi/default.sh

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