Fedora Linux

Chapter 3. Using Fedora on Your Notebook

Notebook systems are becoming more like desktop systems with each generation, and many notebooks have CPU, memory, disk, and video capabilities that make them true desktop replacements. But the compact, mobile nature of notebooks requires more complex configurations in order to handle power management, mobile networking, and frequently changing hardware configurations.

Many of the topics in this chapter apply to both desktop and notebook systems (and, to a lesser extent, server systems), but become more complex in a mobile environment.

3.1. Power Management

When you're on the go, you have to carry your power with you. Notebook power management therefore receives a lot more attention than desktop power management, even though attention to these issues on the desktop can result in significant savings in electrical costs, system wear, and heat production.

For many years, power-management interfaces have been proprietary and required custom software supplied by the hardware vendor in order to function well (even when they purportedly adhered to industry standards). The situation is slowly improving, and Fedora contains good tools for power management on well- behaved systems.

3.1.1. How Do I Do That?

Fedora uses the Advanced Configuation and Power Interface (ACPI) specification to monitor and manage the current power configuration. This approach requires support from the motherboard and CPU as well as the operating system; fortunately, most systems built in the last decade have some level of ACPI support, though many BIOS implementations are nonstandard.

3.1.1.1. Using gnome-power-manager to conserve power

Fedora's main power-management tool is gnome-power-manager. You can access the gnome-power-manager configuration window using the menu option System>Preferences>More Preferences>Power Management. 

Fedora Core does not include the KDE ACPI modules. However, you can use gnome-power- manager in KDE by starting it manually: press Alt-F2 or open a terminal, and type:

$ gnome-power-manager

A second power-management icon will appear in the KDE panel. You can disable KDE's icon through the Control Center menu option; go to Power Control>Laptop Battery and deselect the checkbox labeled 'Show battery monitor.'

gnome-power-manager will automatically be started next time you enter KDE. 

The same program controls the power-management icon in the panel bar, which may or may not appear depending on the system configuration (it will usually appear by default on a system that has a battery, including most notebooks, but will not appear by default on a system with no battery). The symbol used for the icon will change according to the power supply: it will show a battery when discharging the battery, a battery plus a power cord when charging the battery, or just a power cord on a system with no battery. You can access the gnome-power-manager configuration window by right-clicking on the icon and selecting Preferences.

Regardless of how you access the configuration window, you will see the display shown in Figure 3-1 .

Figure 3-1. Power Manager Preferences window 

 This window contains three tabs: one that configures power management when the system is running on AC or charging the battery, one that configures power management when the system is running on (and discharging) the battery, and one for general power-management settings.

The controls on first two tabs are almost identical:

Sleep

Configures the conditions under which the display and the whole system is put to sleep. For the display, 'sleep' is defined as a low-power mode; for the system, the definition of 'sleep' is taken from the setting on the General tab. You can set either to a value between 11 and 60 minutes (in one-minute intervals), or you can disable sleep by moving the slider all the way to the right (Never).

When laptop lid is closed

Specifies the action to be taken when a lid closure event is signaled by ACPI. The options include: do nothing, which causes the system to continue to use full power, to be available the moment you open the screen; blank the screen, which is similar to doing nothing but will use slightly less power and delay system startup for a few seconds; or suspend or hibernate the system.

Configuring the screen to blank without suspending or hibernating the system whenever the lid is closed is ideal for listening to digital music. 

Prefer power savings over performance

If you are performing a task that is not very demanding, such as editing a document, instruct gnome-power-manager to maximize the battery life (or, on AC, reduce power consumption) by selecting the checkbox. On the other hand, if you need optimal performance without regard to the power consumptionsuch as when you are giving an important presentationleave the checkbox for this option unselected.

When battery power critical

This button appears only on the 'Running on Battery' tab, and it configures the action to be taken if the battery runs down to the point that it will power the system for only a few minutes. The options are to do nothing, to suspend or hibernate, or to shut down the system. For most users, doing nothing is a poor choice because the system will abruptly shut off within a few minutes; suspend continues to use power, although at a much lower rate than usual, so the battery will ultimately go dead in due course (causing the loss of any data in memory). Shutdown in an option, but the shutdown procedure itself may take a few minutes and uses a fair bit of power. Therefore, the best choice (if your system supports it) is to hibernate the system when the battery power becomes critical. Hibernation takes less than a minute to complete and even less time to resume, yet it uses no power during the time that the system is in hibernation.