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authorLinus Torvalds <torvalds@linux-foundation.org>2013-11-14 08:41:48 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2013-11-14 08:41:48 +0400
commitf9300eaaac1ca300083ad41937923a90cc3a2394 (patch)
tree724b72ad729a8b85c09d2d54f8ca7d8ba22d774f /Documentation/power/powercap/powercap.txt
parent7f2dc5c4bcbff035b0d03f7aa78a182664b21e47 (diff)
parentfaddf2f5d278f1656e9444961bdd8d9db4deb5bf (diff)
downloadlinux-f9300eaaac1ca300083ad41937923a90cc3a2394.tar.xz
Merge tag 'pm+acpi-3.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull ACPI and power management updates from Rafael J Wysocki: - New power capping framework and the the Intel Running Average Power Limit (RAPL) driver using it from Srinivas Pandruvada and Jacob Pan. - Addition of the in-kernel switching feature to the arm_big_little cpufreq driver from Viresh Kumar and Nicolas Pitre. - cpufreq support for iMac G5 from Aaro Koskinen. - Baytrail processors support for intel_pstate from Dirk Brandewie. - cpufreq support for Midway/ECX-2000 from Mark Langsdorf. - ARM vexpress/TC2 cpufreq support from Sudeep KarkadaNagesha. - ACPI power management support for the I2C and SPI bus types from Mika Westerberg and Lv Zheng. - cpufreq core fixes and cleanups from Viresh Kumar, Srivatsa S Bhat, Stratos Karafotis, Xiaoguang Chen, Lan Tianyu. - cpufreq drivers updates (mostly fixes and cleanups) from Viresh Kumar, Aaro Koskinen, Jungseok Lee, Sudeep KarkadaNagesha, Lukasz Majewski, Manish Badarkhe, Hans-Christian Egtvedt, Evgeny Kapaev. - intel_pstate updates from Dirk Brandewie and Adrian Huang. - ACPICA update to version 20130927 includig fixes and cleanups and some reduction of divergences between the ACPICA code in the kernel and ACPICA upstream in order to improve the automatic ACPICA patch generation process. From Bob Moore, Lv Zheng, Tomasz Nowicki, Naresh Bhat, Bjorn Helgaas, David E Box. - ACPI IPMI driver fixes and cleanups from Lv Zheng. - ACPI hotplug fixes and cleanups from Bjorn Helgaas, Toshi Kani, Zhang Yanfei, Rafael J Wysocki. - Conversion of the ACPI AC driver to the platform bus type and multiple driver fixes and cleanups related to ACPI from Zhang Rui. - ACPI processor driver fixes and cleanups from Hanjun Guo, Jiang Liu, Bartlomiej Zolnierkiewicz, Mathieu Rhéaume, Rafael J Wysocki. - Fixes and cleanups and new blacklist entries related to the ACPI video support from Aaron Lu, Felipe Contreras, Lennart Poettering, Kirill Tkhai. - cpuidle core cleanups from Viresh Kumar and Lorenzo Pieralisi. - cpuidle drivers fixes and cleanups from Daniel Lezcano, Jingoo Han, Bartlomiej Zolnierkiewicz, Prarit Bhargava. - devfreq updates from Sachin Kamat, Dan Carpenter, Manish Badarkhe. - Operation Performance Points (OPP) core updates from Nishanth Menon. - Runtime power management core fix from Rafael J Wysocki and update from Ulf Hansson. - Hibernation fixes from Aaron Lu and Rafael J Wysocki. - Device suspend/resume lockup detection mechanism from Benoit Goby. - Removal of unused proc directories created for various ACPI drivers from Lan Tianyu. - ACPI LPSS driver fix and new device IDs for the ACPI platform scan handler from Heikki Krogerus and Jarkko Nikula. - New ACPI _OSI blacklist entry for Toshiba NB100 from Levente Kurusa. - Assorted fixes and cleanups related to ACPI from Andy Shevchenko, Al Stone, Bartlomiej Zolnierkiewicz, Colin Ian King, Dan Carpenter, Felipe Contreras, Jianguo Wu, Lan Tianyu, Yinghai Lu, Mathias Krause, Liu Chuansheng. - Assorted PM fixes and cleanups from Andy Shevchenko, Thierry Reding, Jean-Christophe Plagniol-Villard. * tag 'pm+acpi-3.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (386 commits) cpufreq: conservative: fix requested_freq reduction issue ACPI / hotplug: Consolidate deferred execution of ACPI hotplug routines PM / runtime: Use pm_runtime_put_sync() in __device_release_driver() ACPI / event: remove unneeded NULL pointer check Revert "ACPI / video: Ignore BIOS initial backlight value for HP 250 G1" ACPI / video: Quirk initial backlight level 0 ACPI / video: Fix initial level validity test intel_pstate: skip the driver if ACPI has power mgmt option PM / hibernate: Avoid overflow in hibernate_preallocate_memory() ACPI / hotplug: Do not execute "insert in progress" _OST ACPI / hotplug: Carry out PCI root eject directly ACPI / hotplug: Merge device hot-removal routines ACPI / hotplug: Make acpi_bus_hot_remove_device() internal ACPI / hotplug: Simplify device ejection routines ACPI / hotplug: Fix handle_root_bridge_removal() ACPI / hotplug: Refuse to hot-remove all objects with disabled hotplug ACPI / scan: Start matching drivers after trying scan handlers ACPI: Remove acpi_pci_slot_init() headers from internal.h ACPI / blacklist: fix name of ThinkPad Edge E530 PowerCap: Fix build error with option -Werror=format-security ... Conflicts: arch/arm/mach-omap2/opp.c drivers/Kconfig drivers/spi/spi.c
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+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.