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Mastering Embedded Linux Programming - Second Edition
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For devices operating on battery power, power management is a critical issue: anything we can do to reduce power usage will increase battery life. Even for devices running on mains power, reducing power usage has benefits in reducing the need for cooling and energy costs. In this chapter, I will introduce the four principles of power management:
Putting these into more technical terms, the principles mean that the power management system should endeavor to reduce the CPU clock frequency; during idle periods, it should choose the deepest sleep state possible; it should reduce the load by powering down unused peripherals; and it should be able to put the whole system into a suspend state.
Linux has features that address each of these points. I will describe each one in turn, with examples and advice on how to apply them to an embedded...