admin-guide/pm/cpuidle.rst

23 Since part of the processor hardware is not used in idle states, entering them
39 (program) from memory and executing them, but it need not work this way
49 work physically in parallel with each other, so if each of them executes only
63 instructions from multiple locations in memory and execute them in the same time
70 by one of them, the hardware thread (or CPU) that asked for it is stopped, but
81 *idle* by the Linux kernel when there are no tasks to run on them except for the
99 to allow them to make some progress over time.]
163 ``ladder`` and ``haltpoll``.  Which of them is used by default depends on the
179 decision on which one of them to use has to be made early (on Intel platforms
194 allow them to make reasonable progress in a given time frame is to make them
207 for them to ask the hardware to enter idle states with target residencies above
215 of the CPU time on them is the idle loop.  Since the time of an idle CPU need
279 One of them is used when tasks previously running on the given CPU are waiting
295 and variance of them.  If the variance is small (smaller than 400 square
300 Again, if the variance of them is small (in the above sense), the average is
324 them.  For this purpose, it compares the target residency of each state with
389 hierarchy of units inside them, however.  In those cases asking for an idle
414 deeper the (effective) idle state represented by it.  Each of them contains
463 between them is that the name is expected to be more concise, while the
472 asked for by the other CPUs, so it must be disabled for all of them in order to
473 never be asked for by any of them.  [Note that, due to the way the ``ladder``
524 individual CPUs.  Kernel code (e.g. device drivers) can set both of them with
540 global CPU latency limit and for each individual CPU, aggregates them and
620 and ``idle=nomwait``.  The first two of them disable the ``acpi_idle`` and
648 drivers that can be passed to them via the kernel command line.  Specifically,
655 for any of those idle states or expose them to the governor.  [The behavior of