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authorLinus Torvalds <torvalds@linux-foundation.org>2023-02-21 23:32:05 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2023-02-21 23:32:05 +0300
commit1b72607d7321e66829e11148712b3a2ba1dc83e7 (patch)
tree7fa9633b99a12104605792f60166ce86a1ab082c /Documentation/driver-api
parent88af9b164c7a25a71b1a1a699872b869e2e84c77 (diff)
parent6828e402d06f7c574430b61c05db784cd847b19f (diff)
downloadlinux-1b72607d7321e66829e11148712b3a2ba1dc83e7.tar.xz
Merge tag 'thermal-6.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull thermal control updates from Rafael Wysocki: "The majority of changes here are related to the general switch-over to using arrays of generic trip point structures registered along with a thermal zone instead of trip point callbacks (this has been done mostly by Daniel Lezcano with some help from yours truly on the Intel drivers front). Apart from that and the related reorganization of code, there are some enhancements of the existing driver and a new Mediatek Low Voltage Thermal Sensor (LVTS) driver. The Intel powerclamp undergoes a major rework so it will use the generic idle_inject facility for CPU idle time injection going forward and it will take additional module parameters for specifying the subset of CPUs to be affected by it (work done by Srinivas Pandruvada). Also included are assorted fixes and a whole bunch of cleanups. Specifics: - Rework a large bunch of drivers to use the generic thermal trip structure and use the opportunity to do more cleanups by removing unused functions from the OF code (Daniel Lezcano) - Remove core header inclusion from drivers (Daniel Lezcano) - Fix some locking issues related to the generic thermal trip rework (Johan Hovold) - Fix a crash when requesting the critical temperature on tegra, which is related to the generic trip point work (Jon Hunter) - Clean up thermal device unregistration code (Viresh Kumar) - Fix and clean up thermal control core initialization error code paths (Daniel Lezcano) - Relocate the trip points handling code into a separate file (Daniel Lezcano) - Make the thermal core fail registration of thermal zones and cooling devices if the thermal class has not been registered (Rafael Wysocki) - Add trip point initialization helper functions for ACPI-defined trip points and modify two thermal drivers to use them (Rafael Wysocki, Daniel Lezcano) - Make the core thermal control code use sysfs_emit_at() instead of scnprintf() where applicable (ye xingchen) - Consolidate code accessing the Intel TCC (Thermal Control Circuitry) MSRs by introducing library functions for that and making the TCC-related code in thermal drivers use them (Zhang Rui) - Enhance the x86_pkg_temp_thermal driver to support dynamic tjmax changes (Zhang Rui) - Address an "unsigned expression compared with zero" warning in the intel_soc_dts_iosf thermal driver (Yang Li) - Update comments regarding two functions in the Intel Menlow thermal driver (Deming Wang) - Use sysfs_emit_at() instead of scnprintf() in the int340x thermal driver (ye xingchen) - Make the intel_pch thermal driver support the Wellsburg PCH (Tim Zimmermann) - Modify the intel_pch and processor_thermal_device_pci thermal drivers use generic trip point tables instead of thermal zone trip point callbacks (Daniel Lezcano) - Add production mode attribute sysfs attribute to the int340x thermal driver (Srinivas Pandruvada) - Rework dynamic trip point updates handling and locking in the int340x thermal driver (Rafael Wysocki) - Make the int340x thermal driver use a generic trip points table instead of thermal zone trip point callbacks (Rafael Wysocki, Daniel Lezcano) - Clean up and improve the int340x thermal driver (Rafael Wysocki) - Simplify and clean up the intel_pch thermal driver (Rafael Wysocki) - Fix the Intel powerclamp thermal driver and make it use the common idle injection framework (Srinivas Pandruvada) - Add two module parameters, cpumask and max_idle, to the Intel powerclamp thermal driver to allow it to affect only a specific subset of CPUs instead of all of them (Srinivas Pandruvada) - Make the Intel quark_dts thermal driver Use generic trip point objects instead of its own trip point representation (Daniel Lezcano) - Add toctree entry for thermal documents and fix two issues in the Intel powerclamp driver documentation (Bagas Sanjaya) - Use strscpy() to instead of strncpy() in the thermal core (Xu Panda) - Fix thermal_sampling_exit() (Vincent Guittot) - Add Mediatek Low Voltage Thermal Sensor (LVTS) driver (Balsam Chihi) - Add r8a779g0 RCar support to the rcar_gen3 thermal driver (Geert Uytterhoeven) - Fix useless call to set_trips() when resuming in the rcar_gen3 thermal control driver and add interrupt support detection at init time to it (Niklas Söderlund) - Fix memory corruption in the hi3660 thermal driver (Yongqin Liu) - Fix include path for libnl3 in pkg-config file for libthermal (Vibhav Pant) - Remove syscfg-based driver for st as the platform is not supported any more (Alain Volmat)" * tag 'thermal-6.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (135 commits) thermal/drivers/st: Remove syscfg based driver thermal: Remove core header inclusion from drivers tools/lib/thermal: Fix include path for libnl3 in pkg-config file. thermal/drivers/hisi: Drop second sensor hi3660 thermal/drivers/rcar_gen3_thermal: Fix device initialization thermal/drivers/rcar_gen3_thermal: Create device local ops struct thermal/drivers/rcar_gen3_thermal: Do not call set_trips() when resuming thermal/drivers/rcar_gen3: Add support for R-Car V4H dt-bindings: thermal: rcar-gen3-thermal: Add r8a779g0 support thermal/drivers/mediatek: Add the Low Voltage Thermal Sensor driver dt-bindings: thermal: mediatek: Add LVTS thermal controllers thermal/drivers/mediatek: Relocate driver to mediatek folder tools/lib/thermal: Fix thermal_sampling_exit() Documentation: powerclamp: Fix numbered lists formatting Documentation: powerclamp: Escape wildcard in cpumask description Documentation: admin-guide: Add toctree entry for thermal docs thermal: intel: powerclamp: Add two module parameters Documentation: admin-guide: Move intel_powerclamp documentation thermal: core: Use sysfs_emit_at() instead of scnprintf() thermal: intel: powerclamp: Fix duration module parameter ...
Diffstat (limited to 'Documentation/driver-api')
-rw-r--r--Documentation/driver-api/thermal/index.rst1
-rw-r--r--Documentation/driver-api/thermal/intel_dptf.rst3
-rw-r--r--Documentation/driver-api/thermal/intel_powerclamp.rst320
3 files changed, 3 insertions, 321 deletions
diff --git a/Documentation/driver-api/thermal/index.rst b/Documentation/driver-api/thermal/index.rst
index 030306ffa408..a886028014ab 100644
--- a/Documentation/driver-api/thermal/index.rst
+++ b/Documentation/driver-api/thermal/index.rst
@@ -14,7 +14,6 @@ Thermal
exynos_thermal
exynos_thermal_emulation
- intel_powerclamp
nouveau_thermal
x86_pkg_temperature_thermal
intel_dptf
diff --git a/Documentation/driver-api/thermal/intel_dptf.rst b/Documentation/driver-api/thermal/intel_dptf.rst
index 372bdb4d04c6..f5c193cccbda 100644
--- a/Documentation/driver-api/thermal/intel_dptf.rst
+++ b/Documentation/driver-api/thermal/intel_dptf.rst
@@ -84,6 +84,9 @@ DPTF ACPI Drivers interface
https:/github.com/intel/thermal_daemon for decoding
thermal table.
+``production_mode`` (RO)
+ When different from zero, manufacturer locked thermal configuration
+ from further changes.
ACPI Thermal Relationship table interface
------------------------------------------
diff --git a/Documentation/driver-api/thermal/intel_powerclamp.rst b/Documentation/driver-api/thermal/intel_powerclamp.rst
deleted file mode 100644
index 3f6dfb0b3ea6..000000000000
--- a/Documentation/driver-api/thermal/intel_powerclamp.rst
+++ /dev/null
@@ -1,320 +0,0 @@
-=======================
-Intel Powerclamp Driver
-=======================
-
-By:
- - Arjan van de Ven <arjan@linux.intel.com>
- - Jacob Pan <jacob.jun.pan@linux.intel.com>
-
-.. Contents:
-
- (*) Introduction
- - Goals and Objectives
-
- (*) Theory of Operation
- - Idle Injection
- - Calibration
-
- (*) Performance Analysis
- - Effectiveness and Limitations
- - Power vs Performance
- - Scalability
- - Calibration
- - Comparison with Alternative Techniques
-
- (*) Usage and Interfaces
- - Generic Thermal Layer (sysfs)
- - Kernel APIs (TBD)
-
-INTRODUCTION
-============
-
-Consider the situation where a system’s power consumption must be
-reduced at runtime, due to power budget, thermal constraint, or noise
-level, and where active cooling is not preferred. Software managed
-passive power reduction must be performed to prevent the hardware
-actions that are designed for catastrophic scenarios.
-
-Currently, P-states, T-states (clock modulation), and CPU offlining
-are used for CPU throttling.
-
-On Intel CPUs, C-states provide effective power reduction, but so far
-they’re only used opportunistically, based on workload. With the
-development of intel_powerclamp driver, the method of synchronizing
-idle injection across all online CPU threads was introduced. The goal
-is to achieve forced and controllable C-state residency.
-
-Test/Analysis has been made in the areas of power, performance,
-scalability, and user experience. In many cases, clear advantage is
-shown over taking the CPU offline or modulating the CPU clock.
-
-
-THEORY OF OPERATION
-===================
-
-Idle Injection
---------------
-
-On modern Intel processors (Nehalem or later), package level C-state
-residency is available in MSRs, thus also available to the kernel.
-
-These MSRs are::
-
- #define MSR_PKG_C2_RESIDENCY 0x60D
- #define MSR_PKG_C3_RESIDENCY 0x3F8
- #define MSR_PKG_C6_RESIDENCY 0x3F9
- #define MSR_PKG_C7_RESIDENCY 0x3FA
-
-If the kernel can also inject idle time to the system, then a
-closed-loop control system can be established that manages package
-level C-state. The intel_powerclamp driver is conceived as such a
-control system, where the target set point is a user-selected idle
-ratio (based on power reduction), and the error is the difference
-between the actual package level C-state residency ratio and the target idle
-ratio.
-
-Injection is controlled by high priority kernel threads, spawned for
-each online CPU.
-
-These kernel threads, with SCHED_FIFO class, are created to perform
-clamping actions of controlled duty ratio and duration. Each per-CPU
-thread synchronizes its idle time and duration, based on the rounding
-of jiffies, so accumulated errors can be prevented to avoid a jittery
-effect. Threads are also bound to the CPU such that they cannot be
-migrated, unless the CPU is taken offline. In this case, threads
-belong to the offlined CPUs will be terminated immediately.
-
-Running as SCHED_FIFO and relatively high priority, also allows such
-scheme to work for both preemptable and non-preemptable kernels.
-Alignment of idle time around jiffies ensures scalability for HZ
-values. This effect can be better visualized using a Perf timechart.
-The following diagram shows the behavior of kernel thread
-kidle_inject/cpu. During idle injection, it runs monitor/mwait idle
-for a given "duration", then relinquishes the CPU to other tasks,
-until the next time interval.
-
-The NOHZ schedule tick is disabled during idle time, but interrupts
-are not masked. Tests show that the extra wakeups from scheduler tick
-have a dramatic impact on the effectiveness of the powerclamp driver
-on large scale systems (Westmere system with 80 processors).
-
-::
-
- CPU0
- ____________ ____________
- kidle_inject/0 | sleep | mwait | sleep |
- _________| |________| |_______
- duration
- CPU1
- ____________ ____________
- kidle_inject/1 | sleep | mwait | sleep |
- _________| |________| |_______
- ^
- |
- |
- roundup(jiffies, interval)
-
-Only one CPU is allowed to collect statistics and update global
-control parameters. This CPU is referred to as the controlling CPU in
-this document. The controlling CPU is elected at runtime, with a
-policy that favors BSP, taking into account the possibility of a CPU
-hot-plug.
-
-In terms of dynamics of the idle control system, package level idle
-time is considered largely as a non-causal system where its behavior
-cannot be based on the past or current input. Therefore, the
-intel_powerclamp driver attempts to enforce the desired idle time
-instantly as given input (target idle ratio). After injection,
-powerclamp monitors the actual idle for a given time window and adjust
-the next injection accordingly to avoid over/under correction.
-
-When used in a causal control system, such as a temperature control,
-it is up to the user of this driver to implement algorithms where
-past samples and outputs are included in the feedback. For example, a
-PID-based thermal controller can use the powerclamp driver to
-maintain a desired target temperature, based on integral and
-derivative gains of the past samples.
-
-
-
-Calibration
------------
-During scalability testing, it is observed that synchronized actions
-among CPUs become challenging as the number of cores grows. This is
-also true for the ability of a system to enter package level C-states.
-
-To make sure the intel_powerclamp driver scales well, online
-calibration is implemented. The goals for doing such a calibration
-are:
-
-a) determine the effective range of idle injection ratio
-b) determine the amount of compensation needed at each target ratio
-
-Compensation to each target ratio consists of two parts:
-
- a) steady state error compensation
- This is to offset the error occurring when the system can
- enter idle without extra wakeups (such as external interrupts).
-
- b) dynamic error compensation
- When an excessive amount of wakeups occurs during idle, an
- additional idle ratio can be added to quiet interrupts, by
- slowing down CPU activities.
-
-A debugfs file is provided for the user to examine compensation
-progress and results, such as on a Westmere system::
-
- [jacob@nex01 ~]$ cat
- /sys/kernel/debug/intel_powerclamp/powerclamp_calib
- controlling cpu: 0
- pct confidence steady dynamic (compensation)
- 0 0 0 0
- 1 1 0 0
- 2 1 1 0
- 3 3 1 0
- 4 3 1 0
- 5 3 1 0
- 6 3 1 0
- 7 3 1 0
- 8 3 1 0
- ...
- 30 3 2 0
- 31 3 2 0
- 32 3 1 0
- 33 3 2 0
- 34 3 1 0
- 35 3 2 0
- 36 3 1 0
- 37 3 2 0
- 38 3 1 0
- 39 3 2 0
- 40 3 3 0
- 41 3 1 0
- 42 3 2 0
- 43 3 1 0
- 44 3 1 0
- 45 3 2 0
- 46 3 3 0
- 47 3 0 0
- 48 3 2 0
- 49 3 3 0
-
-Calibration occurs during runtime. No offline method is available.
-Steady state compensation is used only when confidence levels of all
-adjacent ratios have reached satisfactory level. A confidence level
-is accumulated based on clean data collected at runtime. Data
-collected during a period without extra interrupts is considered
-clean.
-
-To compensate for excessive amounts of wakeup during idle, additional
-idle time is injected when such a condition is detected. Currently,
-we have a simple algorithm to double the injection ratio. A possible
-enhancement might be to throttle the offending IRQ, such as delaying
-EOI for level triggered interrupts. But it is a challenge to be
-non-intrusive to the scheduler or the IRQ core code.
-
-
-CPU Online/Offline
-------------------
-Per-CPU kernel threads are started/stopped upon receiving
-notifications of CPU hotplug activities. The intel_powerclamp driver
-keeps track of clamping kernel threads, even after they are migrated
-to other CPUs, after a CPU offline event.
-
-
-Performance Analysis
-====================
-This section describes the general performance data collected on
-multiple systems, including Westmere (80P) and Ivy Bridge (4P, 8P).
-
-Effectiveness and Limitations
------------------------------
-The maximum range that idle injection is allowed is capped at 50
-percent. As mentioned earlier, since interrupts are allowed during
-forced idle time, excessive interrupts could result in less
-effectiveness. The extreme case would be doing a ping -f to generated
-flooded network interrupts without much CPU acknowledgement. In this
-case, little can be done from the idle injection threads. In most
-normal cases, such as scp a large file, applications can be throttled
-by the powerclamp driver, since slowing down the CPU also slows down
-network protocol processing, which in turn reduces interrupts.
-
-When control parameters change at runtime by the controlling CPU, it
-may take an additional period for the rest of the CPUs to catch up
-with the changes. During this time, idle injection is out of sync,
-thus not able to enter package C- states at the expected ratio. But
-this effect is minor, in that in most cases change to the target
-ratio is updated much less frequently than the idle injection
-frequency.
-
-Scalability
------------
-Tests also show a minor, but measurable, difference between the 4P/8P
-Ivy Bridge system and the 80P Westmere server under 50% idle ratio.
-More compensation is needed on Westmere for the same amount of
-target idle ratio. The compensation also increases as the idle ratio
-gets larger. The above reason constitutes the need for the
-calibration code.
-
-On the IVB 8P system, compared to an offline CPU, powerclamp can
-achieve up to 40% better performance per watt. (measured by a spin
-counter summed over per CPU counting threads spawned for all running
-CPUs).
-
-Usage and Interfaces
-====================
-The powerclamp driver is registered to the generic thermal layer as a
-cooling device. Currently, it’s not bound to any thermal zones::
-
- jacob@chromoly:/sys/class/thermal/cooling_device14$ grep . *
- cur_state:0
- max_state:50
- type:intel_powerclamp
-
-cur_state allows user to set the desired idle percentage. Writing 0 to
-cur_state will stop idle injection. Writing a value between 1 and
-max_state will start the idle injection. Reading cur_state returns the
-actual and current idle percentage. This may not be the same value
-set by the user in that current idle percentage depends on workload
-and includes natural idle. When idle injection is disabled, reading
-cur_state returns value -1 instead of 0 which is to avoid confusing
-100% busy state with the disabled state.
-
-Example usage:
-- To inject 25% idle time::
-
- $ sudo sh -c "echo 25 > /sys/class/thermal/cooling_device80/cur_state
-
-If the system is not busy and has more than 25% idle time already,
-then the powerclamp driver will not start idle injection. Using Top
-will not show idle injection kernel threads.
-
-If the system is busy (spin test below) and has less than 25% natural
-idle time, powerclamp kernel threads will do idle injection. Forced
-idle time is accounted as normal idle in that common code path is
-taken as the idle task.
-
-In this example, 24.1% idle is shown. This helps the system admin or
-user determine the cause of slowdown, when a powerclamp driver is in action::
-
-
- Tasks: 197 total, 1 running, 196 sleeping, 0 stopped, 0 zombie
- Cpu(s): 71.2%us, 4.7%sy, 0.0%ni, 24.1%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
- Mem: 3943228k total, 1689632k used, 2253596k free, 74960k buffers
- Swap: 4087804k total, 0k used, 4087804k free, 945336k cached
-
- PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
- 3352 jacob 20 0 262m 644 428 S 286 0.0 0:17.16 spin
- 3341 root -51 0 0 0 0 D 25 0.0 0:01.62 kidle_inject/0
- 3344 root -51 0 0 0 0 D 25 0.0 0:01.60 kidle_inject/3
- 3342 root -51 0 0 0 0 D 25 0.0 0:01.61 kidle_inject/1
- 3343 root -51 0 0 0 0 D 25 0.0 0:01.60 kidle_inject/2
- 2935 jacob 20 0 696m 125m 35m S 5 3.3 0:31.11 firefox
- 1546 root 20 0 158m 20m 6640 S 3 0.5 0:26.97 Xorg
- 2100 jacob 20 0 1223m 88m 30m S 3 2.3 0:23.68 compiz
-
-Tests have shown that by using the powerclamp driver as a cooling
-device, a PID based userspace thermal controller can manage to
-control CPU temperature effectively, when no other thermal influence
-is added. For example, a UltraBook user can compile the kernel under
-certain temperature (below most active trip points).