June 2017
Intermediate to advanced
478 pages
13h 14m
English
Content preview from Mastering Embedded Linux Programming - Second Edition
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The CPUIdle driver
As with the CPUFreq subsystem, CPUIdle consists of a driver that is part of the BSP and a governor that determines the policy. Unlike CPUFreq, however, the governor cannot be changed at runtime and there is no interface for user space governors.
CPUIdle exposes information about each of the idle states in the /sys/devices/system/cpu/cpu0/cpuidle directory, in which there is a subdirectory for each of the sleep states, named state0 to stateN. state0 is the lightest sleep and stateN the deepest. Note that the numbering does not match that of the C-states and that CPUIdle does not have a state equivalent to C0 (running). For each state, there are these files:
- desc: A short description of the state
- disable: An option to disable ...
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