# GNOME Power Manager Manual

GNOME Power Manager is a session daemon for the GNOME Desktop that manages the power settings for your laptop or desktop computer.

2006-2009
Richard Hughes (richard@hughsie.com)
2009
Philip Withnall (philip@tecnocode.co.uk)
Richard Hughes

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Richard
Hughes
richard@hughsie.com
2.0
2006-08-30

Richard Hughes richard@hughsie.com

Richard Hughes

## Feedback

To report a bug or make a suggestion regarding the GNOME Power Manager application or this manual, follow the directions in the GNOME Power Manager Contact Page.

## Introduction

The GNOME Power Manager session daemon is a power management daemon for the GNOME desktop

## Usage

GNOME Power Manager is usually started in GNOME startup, but you can manually start GNOME Power Manager by doing:

Command line

  Type `gnome-power-manager --verbose --no-daemon`, then press Return:

## Notification Messages

When GNOME Power Manager has started, the following notifications may be displayed.

### AC Adapter Unplugged

#### GNOME Power Manager Notification when AC adapter is removed

You can disable this notification by changing the GConf key `/apps/gnome-power-manager/notify/discharging`.

### Fully Charged

#### GNOME Power Manager Notification when laptop primary battery is fully charged

You can disable this notification by changing the GConf key `/apps/gnome-power-manager/notify/fully_charged`.

You will only get a repeat notification if your battery percentage charge drops below 95% and then is again fully charged. This prevents some machines from showing unwanted repeat notifications if the battery is incorrectly reporting the charged status.

### Power Low

When the battery is low, you will receive the following notification. You should consider switching to AC power really soon.

#### GNOME Power Manager Notification when battery power is low

You can disable this notification by changing the GConf key `/apps/gnome-power-manager/notify/low_power`.

### Power Critical

When the computer has run out of power, it will show this notification explaining what action is required. You can change the critical low action using the preferences tool.

#### GNOME Power Manager Notification when the system power is critically low

### Suspend Failure

When a suspend failure occurs you may get this following warning. The most common reason for this notification is that the current user does not have permission to suspend or hibernate the computer.

#### GNOME Power Manager Notification when suspend failure occurs

You can disable this notification by changing the GConf key `/apps/gnome-power-manager/notify/sleep_failed`.

## Statistics

The statistics program allows you to visualise the power consumption of your laptop hardware.

This has been removed from the information window of previous versions of GNOME Power Manager as the data interface is now using DBus rather than internal IPC. This allows other applications to query and display the data if required.

### Power History going from battery power to AC

You may not see some options or graphs if your computer does not have the required hardware. You may also see other hardware not shown here (for example UPS devices) but these are treated the same way as other devices.

### Charge History

This graph shows the percentage charge available for the composite primary battery, so if you have a main laptop battery and an auxiliary battery then only the averaged value will be shown. A legend is not shown with this graph.

### Power History

This graph shows the power history charge used by the composite primary battery. This line represents the amount of power that is either being used to charge the batteries in the system, or the power being used by the system from the batteries. You should see the line go up when processor-intensive tasks are performed, and down when the system is idle, or when the screen is dimmed. A legend is shown with this graph when data events have been received.

You do will not receive rate data from your computer if it is not charging or discharging, or if the computer is suspended. This is due to hardware limitations where the rate is only sent from the battery management chip, rather than the power management chip on the motherboard.

### Estimated Time History

This graph shows the estimated charge history for the composite primary battery. This line represents the amount of time required until charged, or the amount of time until discharge. This line should go proportionally up when the rate decreases and down when the rate increases. A legend is shown with this graph when data events have been received.

## Preferences

The preferences window allows you to control:

- The LCD brightness when on AC and battery power

- The idle time for the screen power-down and suspend action

- The actions to perform when the laptop lid is closed

- The notification area icon policy

Some sliders or option boxes may be disabled if the GConf policy keys are not writable. This allows administrators to lock-down the actions that a user can select.

### AC Preferences

#### GNOME Power Manager AC tab

### Battery Preferences

#### GNOME Power Manager battery tab

This allows a powerful computer to reduce the power usage when idle, or when the full capabilities are not required.

### General Preferences

#### GNOME Power Manager general tab

### Session and system idle times

`gnome-screensaver` is a session daemon that monitors user input, and if the mouse has not been moved, or the keyboard been pressed then it starts a timeout. When the value of this timeout reaches the value set in `gnome-screensaver-preferences`, then the login is marked as 'session idle'. This is when GNOME Power Manager performs all the session idle actions such as enabling low-power mode and lowering the laptop panel brightness.

#### Changing the session idle timeout in `gnome-screensaver-preferences`

As soon as the session is marked as idle, GNOME Power Manager starts its own 'system' timer. When the timeout set in `gnome-power-preferences` is reached, and the CPU load is idle, then the idle action is performed, which is usually to turn off the screen, or to suspend or hibernate.

To make this clearer, the sliders in `gnome-power-preferences` are set to start at the value of the session-timeout plus one minute, as we cannot logically trigger before the session is marked as idle. If you adjust the value of the 'session idle' timeout in `gnome-screensaver-preferences` then the start of the sliders in `gnome-power-preferences` will change accordingly.

## Advanced Preferences

### Screen Dim Brightness

You can change the idle laptop panel brightness by changing the GConf key `/apps/gnome-power-manager/backlight/idle_brightness`.

### Screen Locking

By default, GNOME Power Manager supports a simple locking scheme. This means that the screen will lock if set to Lock screen in gnome-screensaver when the lid is closed, or the system performs a suspend or hibernate action.

There is a complex locking scheme available for power users that allows locking policy to change for the lid, suspend and hibernate actions. To enable this complex mode, you will have to disable the GConf key:

- `/apps/gnome-power-manager/lock/use_screensaver_settings`

Then the policy keys can be set to force a gnome-screensaver lock and unlock when the action is performed:

- `/apps/gnome-power-manager/lock/blank_screen`

- `/apps/gnome-power-manager/lock/suspend`

- `/apps/gnome-power-manager/lock/hibernate`

The lock policy for gnome-screensaver is ignored until the simple mode is re-enabled.

## GNOME Power Applets

### Brightness Applet

The brightness applet allows the user to change the brightness temporarily without changing the default policy. This may be useful if you have got a laptop without brightness buttons, as you can now change the brightness easily.

#### Brightness applet drop-down.

You will not get the slider if your hardware is not supported.

### Inhibit Applet

The inhibit applet allows the user to prevent the computer auto-sleeping when inactive. This may be required with old or proprietary programs such as VMWare or Matlab. Just click the icon for the auto-suspend to be inhibited, and click it again for normal operation.

#### Inhibit applet in inhibited state.

Don't use this applet if you just use GNOME software; instead file a bug to make the application use the `Inhibit()` and `UnInhibit()` methods as this should 'just work'.

## Frequently Asked Questions

These are questions the mailing list gets asked frequently.

### What is battery capacity?

Capacity is how much charge your battery can store compared to its manufacturer's guidelines.

#### This graph shows the capacity of a typical lithium ion battery over a few hundred charge-discharge cycles.

### What's the difference between suspend and hibernate?

The Suspend state is a power saving feature which is the lowest level of power consumption that preserves program data in the computer's memory. When your computer is in the Suspended state, computation will not be performed until normal activity is resumed. It will not resume until signalled by an external event such as a keyboard button press. It generally takes a few seconds to suspend and then resume your computer.

You still use a small amount of battery power while suspended, so is not recommended for the low power action. If you remove AC power on a desktop, or run out of battery power on a laptop then you will lose your work.

The Hibernation state saves the complete state of the computer to hard disk and turns off the power, so that the computer appears to be off. It will not resume until signalled by an external event such as a keyboard button press. This is the lowest power sleeping state available. If you remove AC power on a desktop, or run out of battery power on a laptop then work will not be lost. It can take up to a minute or more to hibernate and wake your computer.

### My monitor is broken and treats DPMS standby and off states as 'no-signal' which leaves the monitor powered on.

You have to change the DPMS suspend mode GNOME Power Manager uses. Open `gconf-editor`, and then change the keys `/apps/gnome-power-manager/backlight/dpms_method_ac` and `/apps/gnome-power-manager/backlight/dpms_method_battery` to one of the modes that work, e.g. standby, suspend or off.

### My time to discharge is always incorrect due to a faulty battery, what can I do?

You might be able to use the percentage charge for GNOME Power Manager to use as the policy data. Open `gconf-editor`, and then change the key `/apps/gnome-power-manager/general/use_time_for_policy` to false. You can do this easily by doing: `gconftool-2 --set --type bool /apps/gnome-power-manager/general/use_time_for_policy false`

This should get the policy actions working for you, but of course the time remaining will still be incorrect.

### How do I make my application stop the computer auto-suspending?

If your application is doing a long operation, you might want to disable the ability to suspend for a little while. You should use gnome-session if you really don't want the user to be able to suspend, or for the computer to save power by hibernating or suspending.

### I'm running ACPI. Why do events (such as removing the AC adapter) take so long to register?

One of two things might be the problem.

- HAL might not be running the addon that captures the ACPI event.

- Your BIOS could be faulty, and might need a work-around. Please file a bug report.

For the first case, try to find the HAL processes that are running: `ps -eaf | grep hal`

And check for the process `hald-addon-acpi`. If it is not being run, then please make sure that HAL is being run with the `--retain-privileges` option in the `haldaemon` initscript. An alternative to this is to use acpid, rather than the kernel proc file.

## About

GNOME Power Manager was written by Richard Hughes richard@hughsie.com. To find more information about GNOME Power Manager, please visit the GNOME Power Manager web page.

To report a bug or make a suggestion regarding this application or this manual, follow the directions at the GNOME Power Manager Bug Page.

This program is distributed under the terms of the GNU General Public licence as published by the Free Software Foundation; either version 2 of the Licence, or (at your option) any later version. A copy of this licence can be found at this link, or in the file COPYING included with the source code of this program.