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Documentation: cpuidle: update the document

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Update the document after the remove of cpuidle_sysfs_switch.

Signed-off-by: Hanjun Guo <guohanjun@huawei.com>
Reviewed-by: Doug Smythies <dsmythies@telus.net>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Hanjun Guo 2020-05-19 14:25:24 +08:00 committed by Rafael J. Wysocki
parent cce55cc902
commit 7395683a24
3 changed files with 20 additions and 29 deletions
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24
Documentation/ABI/testing/sysfs-devices-system-cpu
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@ -106,10 +106,10 @@ Description: CPU topology files that describe a logical CPU's relationship
See Documentation/admin-guide/cputopology.rst for more information.
What: /sys/devices/system/cpu/cpuidle/current_driver
/sys/devices/system/cpu/cpuidle/current_governer_ro
/sys/devices/system/cpu/cpuidle/available_governors
What: /sys/devices/system/cpu/cpuidle/available_governors
/sys/devices/system/cpu/cpuidle/current_driver
/sys/devices/system/cpu/cpuidle/current_governor
/sys/devices/system/cpu/cpuidle/current_governer_ro
Date: September 2007
Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
Description: Discover cpuidle policy and mechanism
@ -119,24 +119,18 @@ Description: Discover cpuidle policy and mechanism
consumption during idle.
Idle policy (governor) is differentiated from idle mechanism
(driver)
current_driver: (RO) displays current idle mechanism
current_governor_ro: (RO) displays current idle policy
With the cpuidle_sysfs_switch boot option enabled (meant for
developer testing), the following three attributes are visible
instead:
current_driver: same as described above
(driver).
available_governors: (RO) displays a space separated list of
available governors
available governors.
current_driver: (RO) displays current idle mechanism.
current_governor: (RW) displays current idle policy. Users can
switch the governor at runtime by writing to this file.
current_governor_ro: (RO) displays current idle policy.
See Documentation/admin-guide/pm/cpuidle.rst and
Documentation/driver-api/pm/cpuidle.rst for more information.

20
Documentation/admin-guide/pm/cpuidle.rst
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@ -159,17 +159,15 @@ governor uses that information depends on what algorithm is implemented by it
and that is the primary reason for having more than one governor in the
``CPUIdle`` subsystem.
There are three ``CPUIdle`` governors available, ``menu``, `TEO <teo-gov_>`_
and ``ladder``. Which of them is used by default depends on the configuration
of the kernel and in particular on whether or not the scheduler tick can be
`stopped by the idle loop <idle-cpus-and-tick_>`_. It is possible to change the
governor at run time if the ``cpuidle_sysfs_switch`` command line parameter has
been passed to the kernel, but that is not safe in general, so it should not be
done on production systems (that may change in the future, though). The name of
the ``CPUIdle`` governor currently used by the kernel can be read from the
:file:`current_governor_ro` (or :file:`current_governor` if
``cpuidle_sysfs_switch`` is present in the kernel command line) file under
:file:`/sys/devices/system/cpu/cpuidle/` in ``sysfs``.
There are four ``CPUIdle`` governors available, ``menu``, `TEO <teo-gov_>`_,
``ladder`` and ``haltpoll``. Which of them is used by default depends on the
configuration of the kernel and in particular on whether or not the scheduler
tick can be `stopped by the idle loop <idle-cpus-and-tick_>`_. Available
governors can be read from the :file:`available_governors`, and the governor
can be changed at runtime. The name of the ``CPUIdle`` governor currently
used by the kernel can be read from the :file:`current_governor_ro` or
:file:`current_governor` file under :file:`/sys/devices/system/cpu/cpuidle/`
in ``sysfs``.
Which ``CPUIdle`` driver is used, on the other hand, usually depends on the
platform the kernel is running on, but there are platforms with more than one

5
Documentation/driver-api/pm/cpuidle.rst
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@ -68,9 +68,8 @@ only one in the list (that is, the list was empty before) or the value of its
governor currently in use, or the name of the new governor was passed to the
kernel as the value of the ``cpuidle.governor=`` command line parameter, the new
governor will be used from that point on (there can be only one ``CPUIdle``
governor in use at a time). Also, if ``cpuidle_sysfs_switch`` is passed to the
kernel in the command line, user space can choose the ``CPUIdle`` governor to
use at run time via ``sysfs``.
governor in use at a time). Also, user space can choose the ``CPUIdle``
governor to use at run time via ``sysfs``.
Once registered, ``CPUIdle`` governors cannot be unregistered, so it is not
practical to put them into loadable kernel modules.