SUSE Linux 10.0 Unleashed

There's no getting around this fact: Computers and peripherals consume a lot of electricity. With dwindling supplies of fossil fuels leading to ever-higher energy bills, it's good to minimize the power drain.

We are in a transition phase for power management on PCs and laptops, with one standard replacing another. Advanced Power Management (APM) is supported by most hardware manufacturers and BIOS routines.

Advanced Configuration and Power Interface (ACPI) is a power-management specification that allows the operating system (OS) to control the amount of power distributed to the computer's devices. Devices not in use can be turned off, reducing unnecessary power expenditure. ACPI is the latest generation of DOS-based power management software for PCs. ACPI replaces the older Intel APM software utility. ACPI does more than just manage timeouts during periods of inactivity; it dynamically monitors power usage within the computer's systems and assigns power accordingly. ACPI controls are found in your PC's BIOS, and ACPI will work only if supported by the systems BIOS and your systems OS, such as SUSE Linux as of Kernel release 2.6.

Note

One place where ACPI alone is supported is in SUSE Linux for the AMD 64-bit processor.

APM allows workstations and servers to automatically shut down when told to. ACPI provides more control over the process. Depending on your system, you may want to configure for both standards. In this section, you'll learn how to use YaST to configure your desktop PC. In the next, you'll see how to configure your laptop.

YaST Power Management

The Power Management module is located under the System page. It is shown in Figure 4.7.

By default, a PC is set for best performance, but you can adjust this scheme in favor of Powersave (for the least energy consumption) or Acoustic (for quiet operation). The fourth scheme, Presentation, is the same as Performance, but turns the screensaver off. You can add your own scheme or edit existing ones by clicking Edit Schemes.