Linux Notebook Power Management Guide

Linux is a superior open source operating system, with its performance and visibility increasingly high, the most important is the price unmatched advantage, many manufacturers began to launch Linux laptops, and this trend has become increasingly fierce. We know that laptops are limited by battery time, so pay special attention to the power management of the machine. Therefore, this article will discuss how to handle these matters.

I. Overview

In fact, in addition to using the BIOS on the motherboard to manage the power supply, most Linux systems themselves have utility software to manage power supplies to handle various power events, such as:

1. The battery is low--the machine warns, displays the icon, or hangs the hardware.

2. Idle-If the machine is inactive for a period of time, the machine can be dormant (such as turning off the hard drive and disabling audio and network services) to effectively extend battery power.

By detecting whether your notebook uses AC power or battery, you can let the machine into the appropriate power management mode. In Fedora, the tools used to manage and overhaul power issues are:

1. The Advanced Power Management (APM)--APM software consists of the following: a PMD daemon that monitors battery usage; Multiple utility software to display and respond to battery events. They are included in the APMD software package.

2. The Advanced Configuration and Power Interface (ACPI)--acpid event daemon monitors power events on the one hand and sets rules that respond to these events to turn off some hardware or power off the system. ACPI is a more versatile tool software designed to replace APM power management, but it needs to be further refined at the moment.

The 3.hdparm Command--hdparm command can be used to turn on and off power management features. In addition, the command has many options to do such things as stopping the hard disk launcher from turning or letting the hard drive into standby.

It should be explained that when ACPI is used, the operating system is responsible for power management, not the BIOS. Although ACPI is more powerful and flexible in managing power issues, it is not easy for ordinary users to use, such as ACPI, when you have to tell it in person which power events to focus on and how to respond to those events. At present, for ordinary users, APM is not only rich in functionality, but also more user-friendly.

Below we will discuss each of the three common power management tools.