The concept of power management on Linux-based systems
Power management (PM) entails consuming as little power as possible at any time. There are two types of power management that the operating system must handle: Device Power Management and System Power Management.
- Device Power Management: This is device specific. It allows a device to be put in a low-power state while the system is running. This may allow, among other things, part of the device not currently in use to be turned off in order to conserve power, such as the keyboard backlight when you are not typing. Individual device power management may be invoked explicitly on devices regardless of the power management activity, or may happen automatically after a device has been idle for a set amount of time. Device power management is an alias for the so-called Runtime Power Management.
- System Power Management, also known as Sleep States: This enables platforms to enter a system-wide low-power state. In other words...