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1.15 Controlling Your Desktop’s Power Management
GNOME Power Manager is a session daemon for the GNOME desktop that
manages the power settings for your laptop or desktop computer.
GNOME Power Manager is usually started automatically when GNOME starts,
but you can manually start GNOME Power Manager by using the following
command:
gnome-power-manager --verbose --no-daemon
1.15.1 GNOME Power Manager Notification Messages
The GNOME Power Manager displays the following notifications under the
specified conditions:
AC Adapter Unplugged
You can disable this notification by changing the GConf key
/apps/gnome-power-manager/notify_ac_adapter.
Fully Charged
You can disable this notification by changing the GConf key
/apps/gnome-power-manager/notify_fully_charged.
You will receive a repeat notification only 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 as soon as possible.
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 (see
Section 1.15.3, Modifying Power Management Preferences
for more information).
Suspend Failure
When a suspend failure occurs, you might receive 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.
1.15.2 Viewing Power Statistics
The statistics program lets you view the power consumption of your
laptop hardware in graphic form.
To access the statistics graphs, click .
You might not see some options or graphs if your computer does not have
the required hardware. You might also see other hardware not shown here
(for example UPS devices), but these are treated the same way as other
devices.
Change History
This graph shows the percentage charge available for the composite
primary battery. If you have a main laptop battery and an auxiliary
battery, 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. The 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 go down when the system is
at idle (or when the screen is dimmed). A legend is shown with this
graph when data events have been received.
You 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. The line represents the amount of time required until charged,
or the amount of time until discharge. This line should go
proportionally up when the power decreases and down when the rate
increases. A legend is shown with this graph when data events have been
received.
1.15.3 Modifying Power Management Preferences
The Power Management Preferences dialog box lets you control the LCD
brightness when your system is on AC or battery power, the idle time for
the screen power-down and suspend action, the actions to perform when
the laptop lid is closed, and the notification area icon policy.
To access Power Management Preferences, click .
On AC Power Preferences
Use the options on the On AC Power dialog box to automatically put your
computer to sleep when it has been inactive for a specified amount of
time.When your computer is asleep, it is turned on but in a low power
mode. It takes less time for a computer to wake up from sleep than it
does for the computer to start up after being turned off.
You can also set only the display to sleep. If your computer is in the
middle of a task (for example, burning a DVD) that you want to finish
while you are away, set only the display to sleep.
On Battery Power Preferences
Use the options on the On Batter Power dialog box to automatically put
your computer to sleep when it has been inactive for a specified amount
of time, to specify what happens when you laptop lid closed, and what
happens when battery power is critically low.
When your computer is asleep, it is turned on but in a low power mode.
It takes less time for a computer to wake up from sleep than it does
for the computer to start up after being turned off.
You can also set only the display to sleep. If your computer is in the
middle of a task (for example, burning a DVD) that you want to finish
while you are away, set only the display to sleep.
General Preferences
Use the options on the General Power Management Preference dialog box
to configure miscellaneous options related to GNOME Power Manager’s
behavior, such as the actions to perform when the power or suspend
buttons are pressed, if an icon is displayed in the Notification area,
and if sound is used to notify you in the event on an error.
1.15.4 Session and System Idle Times
gnome-screensaver is a session daemon that monitors
user input (if the mouse has or has not been moved, and if the keyboard
has or has not been pressed), then starts a timeout. When the value of
this timeout reaches the value set in Screensaver Preferences (using the
option), then the
login is marked as session idle. At this point, GNOME
Power Manager performs the session idle actions, such as enabling
low-power mode, and lowering the laptop panel brightness.
As soon as the session is marked idle, GNOME Power Manager starts it's
own system timer. When the timeout set in GNOME Power Manager
Preferences is reached, and the CPU load is idle, then the idle action
is performed (such as turning off the screen, suspending, or hibernating
the computer).
To make this clearer, the sliders in GNOME Power Manager Preferences are
set to start at the value of the session-timeout + 1 minute, as GNOME
Power Manager Preferences cannot logically trigger before the session is
marked as idle. If you adjust the value of the session idle timeout in
Screensaver Preferences, the start time of the sliders in GNOME Power
Manager Preferences will change accordingly.
For more information, see
Section 2.3.4, Configuring the Screen Saver.
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