mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-11-24 18:44:07 +08:00
151f4e2bdc
Convert the PM documents to ReST, in order to allow them to build with Sphinx. The conversion is actually: - add blank lines and indentation in order to identify paragraphs; - fix tables markups; - add some lists markups; - mark literal blocks; - adjust title markups. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Acked-by: Mark Brown <broonie@kernel.org> Acked-by: Srivatsa S. Bhat (VMware) <srivatsa@csail.mit.edu>
258 lines
10 KiB
ReStructuredText
258 lines
10 KiB
ReStructuredText
=======================
|
|
Power Capping Framework
|
|
=======================
|
|
|
|
The power capping framework provides a consistent interface between the kernel
|
|
and the user space that allows power capping drivers to expose the settings to
|
|
user space in a uniform way.
|
|
|
|
Terminology
|
|
===========
|
|
|
|
The framework exposes power capping devices to user space via sysfs in the
|
|
form of a tree of objects. The objects at the root level of the tree represent
|
|
'control types', which correspond to different methods of power capping. For
|
|
example, the intel-rapl control type represents the Intel "Running Average
|
|
Power Limit" (RAPL) technology, whereas the 'idle-injection' control type
|
|
corresponds to the use of idle injection for controlling power.
|
|
|
|
Power zones represent different parts of the system, which can be controlled and
|
|
monitored using the power capping method determined by the control type the
|
|
given zone belongs to. They each contain attributes for monitoring power, as
|
|
well as controls represented in the form of power constraints. If the parts of
|
|
the system represented by different power zones are hierarchical (that is, one
|
|
bigger part consists of multiple smaller parts that each have their own power
|
|
controls), those power zones may also be organized in a hierarchy with one
|
|
parent power zone containing multiple subzones and so on to reflect the power
|
|
control topology of the system. In that case, it is possible to apply power
|
|
capping to a set of devices together using the parent power zone and if more
|
|
fine grained control is required, it can be applied through the subzones.
|
|
|
|
|
|
Example sysfs interface tree::
|
|
|
|
/sys/devices/virtual/powercap
|
|
└──intel-rapl
|
|
├──intel-rapl:0
|
|
│ ├──constraint_0_name
|
|
│ ├──constraint_0_power_limit_uw
|
|
│ ├──constraint_0_time_window_us
|
|
│ ├──constraint_1_name
|
|
│ ├──constraint_1_power_limit_uw
|
|
│ ├──constraint_1_time_window_us
|
|
│ ├──device -> ../../intel-rapl
|
|
│ ├──energy_uj
|
|
│ ├──intel-rapl:0:0
|
|
│ │ ├──constraint_0_name
|
|
│ │ ├──constraint_0_power_limit_uw
|
|
│ │ ├──constraint_0_time_window_us
|
|
│ │ ├──constraint_1_name
|
|
│ │ ├──constraint_1_power_limit_uw
|
|
│ │ ├──constraint_1_time_window_us
|
|
│ │ ├──device -> ../../intel-rapl:0
|
|
│ │ ├──energy_uj
|
|
│ │ ├──max_energy_range_uj
|
|
│ │ ├──name
|
|
│ │ ├──enabled
|
|
│ │ ├──power
|
|
│ │ │ ├──async
|
|
│ │ │ []
|
|
│ │ ├──subsystem -> ../../../../../../class/power_cap
|
|
│ │ └──uevent
|
|
│ ├──intel-rapl:0:1
|
|
│ │ ├──constraint_0_name
|
|
│ │ ├──constraint_0_power_limit_uw
|
|
│ │ ├──constraint_0_time_window_us
|
|
│ │ ├──constraint_1_name
|
|
│ │ ├──constraint_1_power_limit_uw
|
|
│ │ ├──constraint_1_time_window_us
|
|
│ │ ├──device -> ../../intel-rapl:0
|
|
│ │ ├──energy_uj
|
|
│ │ ├──max_energy_range_uj
|
|
│ │ ├──name
|
|
│ │ ├──enabled
|
|
│ │ ├──power
|
|
│ │ │ ├──async
|
|
│ │ │ []
|
|
│ │ ├──subsystem -> ../../../../../../class/power_cap
|
|
│ │ └──uevent
|
|
│ ├──max_energy_range_uj
|
|
│ ├──max_power_range_uw
|
|
│ ├──name
|
|
│ ├──enabled
|
|
│ ├──power
|
|
│ │ ├──async
|
|
│ │ []
|
|
│ ├──subsystem -> ../../../../../class/power_cap
|
|
│ ├──enabled
|
|
│ ├──uevent
|
|
├──intel-rapl:1
|
|
│ ├──constraint_0_name
|
|
│ ├──constraint_0_power_limit_uw
|
|
│ ├──constraint_0_time_window_us
|
|
│ ├──constraint_1_name
|
|
│ ├──constraint_1_power_limit_uw
|
|
│ ├──constraint_1_time_window_us
|
|
│ ├──device -> ../../intel-rapl
|
|
│ ├──energy_uj
|
|
│ ├──intel-rapl:1:0
|
|
│ │ ├──constraint_0_name
|
|
│ │ ├──constraint_0_power_limit_uw
|
|
│ │ ├──constraint_0_time_window_us
|
|
│ │ ├──constraint_1_name
|
|
│ │ ├──constraint_1_power_limit_uw
|
|
│ │ ├──constraint_1_time_window_us
|
|
│ │ ├──device -> ../../intel-rapl:1
|
|
│ │ ├──energy_uj
|
|
│ │ ├──max_energy_range_uj
|
|
│ │ ├──name
|
|
│ │ ├──enabled
|
|
│ │ ├──power
|
|
│ │ │ ├──async
|
|
│ │ │ []
|
|
│ │ ├──subsystem -> ../../../../../../class/power_cap
|
|
│ │ └──uevent
|
|
│ ├──intel-rapl:1:1
|
|
│ │ ├──constraint_0_name
|
|
│ │ ├──constraint_0_power_limit_uw
|
|
│ │ ├──constraint_0_time_window_us
|
|
│ │ ├──constraint_1_name
|
|
│ │ ├──constraint_1_power_limit_uw
|
|
│ │ ├──constraint_1_time_window_us
|
|
│ │ ├──device -> ../../intel-rapl:1
|
|
│ │ ├──energy_uj
|
|
│ │ ├──max_energy_range_uj
|
|
│ │ ├──name
|
|
│ │ ├──enabled
|
|
│ │ ├──power
|
|
│ │ │ ├──async
|
|
│ │ │ []
|
|
│ │ ├──subsystem -> ../../../../../../class/power_cap
|
|
│ │ └──uevent
|
|
│ ├──max_energy_range_uj
|
|
│ ├──max_power_range_uw
|
|
│ ├──name
|
|
│ ├──enabled
|
|
│ ├──power
|
|
│ │ ├──async
|
|
│ │ []
|
|
│ ├──subsystem -> ../../../../../class/power_cap
|
|
│ ├──uevent
|
|
├──power
|
|
│ ├──async
|
|
│ []
|
|
├──subsystem -> ../../../../class/power_cap
|
|
├──enabled
|
|
└──uevent
|
|
|
|
The above example illustrates a case in which the Intel RAPL technology,
|
|
available in Intel® IA-64 and IA-32 Processor Architectures, is used. There is one
|
|
control type called intel-rapl which contains two power zones, intel-rapl:0 and
|
|
intel-rapl:1, representing CPU packages. Each of these power zones contains
|
|
two subzones, intel-rapl:j:0 and intel-rapl:j:1 (j = 0, 1), representing the
|
|
"core" and the "uncore" parts of the given CPU package, respectively. All of
|
|
the zones and subzones contain energy monitoring attributes (energy_uj,
|
|
max_energy_range_uj) and constraint attributes (constraint_*) allowing controls
|
|
to be applied (the constraints in the 'package' power zones apply to the whole
|
|
CPU packages and the subzone constraints only apply to the respective parts of
|
|
the given package individually). Since Intel RAPL doesn't provide instantaneous
|
|
power value, there is no power_uw attribute.
|
|
|
|
In addition to that, each power zone contains a name attribute, allowing the
|
|
part of the system represented by that zone to be identified.
|
|
For example::
|
|
|
|
cat /sys/class/power_cap/intel-rapl/intel-rapl:0/name
|
|
|
|
package-0
|
|
---------
|
|
|
|
The Intel RAPL technology allows two constraints, short term and long term,
|
|
with two different time windows to be applied to each power zone. Thus for
|
|
each zone there are 2 attributes representing the constraint names, 2 power
|
|
limits and 2 attributes representing the sizes of the time windows. Such that,
|
|
constraint_j_* attributes correspond to the jth constraint (j = 0,1).
|
|
|
|
For example::
|
|
|
|
constraint_0_name
|
|
constraint_0_power_limit_uw
|
|
constraint_0_time_window_us
|
|
constraint_1_name
|
|
constraint_1_power_limit_uw
|
|
constraint_1_time_window_us
|
|
|
|
Power Zone Attributes
|
|
=====================
|
|
|
|
Monitoring attributes
|
|
---------------------
|
|
|
|
energy_uj (rw)
|
|
Current energy counter in micro joules. Write "0" to reset.
|
|
If the counter can not be reset, then this attribute is read only.
|
|
|
|
max_energy_range_uj (ro)
|
|
Range of the above energy counter in micro-joules.
|
|
|
|
power_uw (ro)
|
|
Current power in micro watts.
|
|
|
|
max_power_range_uw (ro)
|
|
Range of the above power value in micro-watts.
|
|
|
|
name (ro)
|
|
Name of this power zone.
|
|
|
|
It is possible that some domains have both power ranges and energy counter ranges;
|
|
however, only one is mandatory.
|
|
|
|
Constraints
|
|
-----------
|
|
|
|
constraint_X_power_limit_uw (rw)
|
|
Power limit in micro watts, which should be applicable for the
|
|
time window specified by "constraint_X_time_window_us".
|
|
|
|
constraint_X_time_window_us (rw)
|
|
Time window in micro seconds.
|
|
|
|
constraint_X_name (ro)
|
|
An optional name of the constraint
|
|
|
|
constraint_X_max_power_uw(ro)
|
|
Maximum allowed power in micro watts.
|
|
|
|
constraint_X_min_power_uw(ro)
|
|
Minimum allowed power in micro watts.
|
|
|
|
constraint_X_max_time_window_us(ro)
|
|
Maximum allowed time window in micro seconds.
|
|
|
|
constraint_X_min_time_window_us(ro)
|
|
Minimum allowed time window in micro seconds.
|
|
|
|
Except power_limit_uw and time_window_us other fields are optional.
|
|
|
|
Common zone and control type attributes
|
|
---------------------------------------
|
|
|
|
enabled (rw): Enable/Disable controls at zone level or for all zones using
|
|
a control type.
|
|
|
|
Power Cap Client Driver Interface
|
|
=================================
|
|
|
|
The API summary:
|
|
|
|
Call powercap_register_control_type() to register control type object.
|
|
Call powercap_register_zone() to register a power zone (under a given
|
|
control type), either as a top-level power zone or as a subzone of another
|
|
power zone registered earlier.
|
|
The number of constraints in a power zone and the corresponding callbacks have
|
|
to be defined prior to calling powercap_register_zone() to register that zone.
|
|
|
|
To Free a power zone call powercap_unregister_zone().
|
|
To free a control type object call powercap_unregister_control_type().
|
|
Detailed API can be generated using kernel-doc on include/linux/powercap.h.
|