Chapter 10: Linux Kernel Power Management

Mobile devices are becoming increasingly complex with more and more features in order to follow commercial trends and satisfy consumers. While a few parts of such devices run proprietary or bare metal software, most of them run Linux-based operating systems (embedded Linux distributions, Android, to name but a few), and all of them are battery powered. In addition to full functionality and performance, consumers require the longest possible autonomy and long-lasting batteries. It goes without saying that full performance and autonomy (power saving) are two totally incompatible concepts, and that a compromise must be found at all times when using the device. This compromise comes with Power Management, which allows us to deal with the lower consumption possible and device performance without ignoring the time needed for the device to wake up (or to be fully operational) after it has been put in a low-power state.

The Linux kernel comes with...