Merge branches 'intel_pstate', 'pm-cpufreq' and 'pm-cpufreq-sched'

.. |struct cpufreq_policy| replace:: :c:type:`struct cpufreq_policy <cpufreq_policy>`

.. |struct cpufreq_policy| replace:: :c:type:`struct cpufreq_policy <cpufreq_policy>`

.. |intel_pstate| replace:: :doc:`intel_pstate <intel_pstate>`

=======================

=======================

CPU Performance Scaling

CPU Performance Scaling

interface it comes from and may not be easily represented in an abstract,

interface it comes from and may not be easily represented in an abstract,

platform-independent way.  For this reason, ``CPUFreq`` allows scaling drivers

platform-independent way.  For this reason, ``CPUFreq`` allows scaling drivers

to bypass the governor layer and implement their own performance scaling

to bypass the governor layer and implement their own performance scaling

algorithms.  That is done by the ``intel_pstate`` scaling driver.

algorithms.  That is done by the |intel_pstate| scaling driver.

``CPUFreq`` Policy Objects

``CPUFreq`` Policy Objects

into account.  That is achieved by invoking the governor's ``->stop`` and

into account.  That is achieved by invoking the governor's ``->stop`` and

``->start()`` callbacks, in this order, for the entire policy.

``->start()`` callbacks, in this order, for the entire policy.

As mentioned before, the ``intel_pstate`` scaling driver bypasses the scaling

As mentioned before, the |intel_pstate| scaling driver bypasses the scaling

governor layer of ``CPUFreq`` and provides its own P-state selection algorithms.

governor layer of ``CPUFreq`` and provides its own P-state selection algorithms.

Consequently, if ``intel_pstate`` is used, scaling governors are not attached to

Consequently, if |intel_pstate| is used, scaling governors are not attached to

new policy objects.  Instead, the driver's ``->setpolicy()`` callback is invoked

new policy objects.  Instead, the driver's ``->setpolicy()`` callback is invoked

to register per-CPU utilization update callbacks for each policy.  These

to register per-CPU utilization update callbacks for each policy.  These

callbacks are invoked by the CPU scheduler in the same way as for scaling

callbacks are invoked by the CPU scheduler in the same way as for scaling

governors, but in the ``intel_pstate`` case they both determine the P-state to

governors, but in the |intel_pstate| case they both determine the P-state to

use and change the hardware configuration accordingly in one go from scheduler

use and change the hardware configuration accordingly in one go from scheduler

context.

context.

``scaling_available_governors``

``scaling_available_governors``

	List of ``CPUFreq`` scaling governors present in the kernel that can

	List of ``CPUFreq`` scaling governors present in the kernel that can

	be attached to this policy or (if the ``intel_pstate`` scaling driver is

	be attached to this policy or (if the |intel_pstate| scaling driver is

	in use) list of scaling algorithms provided by the driver that can be

	in use) list of scaling algorithms provided by the driver that can be

	applied to this policy.

	applied to this policy.

	the CPU is actually running at (due to hardware design and other

	the CPU is actually running at (due to hardware design and other

	limitations).

	limitations).

	Some scaling drivers (e.g. ``intel_pstate``) attempt to provide

	Some scaling drivers (e.g. |intel_pstate|) attempt to provide

	information more precisely reflecting the current CPU frequency through

	information more precisely reflecting the current CPU frequency through

	this attribute, but that still may not be the exact current CPU

	this attribute, but that still may not be the exact current CPU

	frequency as seen by the hardware at the moment.

	frequency as seen by the hardware at the moment.

``scaling_governor``

``scaling_governor``

	The scaling governor currently attached to this policy or (if the

	The scaling governor currently attached to this policy or (if the

	``intel_pstate`` scaling driver is in use) the scaling algorithm

	|intel_pstate| scaling driver is in use) the scaling algorithm

	provided by the driver that is currently applied to this policy.

	provided by the driver that is currently applied to this policy.

	This attribute is read-write and writing to it will cause a new scaling

	This attribute is read-write and writing to it will cause a new scaling

	governor to be attached to this policy or a new scaling algorithm

	governor to be attached to this policy or a new scaling algorithm

	provided by the scaling driver to be applied to it (in the

	provided by the scaling driver to be applied to it (in the

	``intel_pstate`` case), as indicated by the string written to this

	|intel_pstate| case), as indicated by the string written to this

	attribute (which must be one of the names listed by the

	attribute (which must be one of the names listed by the

	``scaling_available_governors`` attribute described above).

	``scaling_available_governors`` attribute described above).

the "boost" setting for the whole system.  It is not present if the underlying

the "boost" setting for the whole system.  It is not present if the underlying

scaling driver does not support the frequency boost mechanism (or supports it,

scaling driver does not support the frequency boost mechanism (or supports it,

but provides a driver-specific interface for controlling it, like

but provides a driver-specific interface for controlling it, like

``intel_pstate``).

|intel_pstate|).

If the value in this file is 1, the frequency boost mechanism is enabled.  This

If the value in this file is 1, the frequency boost mechanism is enabled.  This

means that either the hardware can be put into states in which it is able to

means that either the hardware can be put into states in which it is able to

   :maxdepth: 2

   :maxdepth: 2

   cpufreq

   cpufreq

   intel_pstate

.. only::  subproject and html

.. only::  subproject and html