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1.. SPDX-License-Identifier: GPL-2.02.. include:: <isonum.txt>3 4===============================================5``amd-pstate`` CPU Performance Scaling Driver6===============================================7 8:Copyright: |copy| 2021 Advanced Micro Devices, Inc.9 10:Author: Huang Rui <ray.huang@amd.com>11 12 13Introduction14===================15 16``amd-pstate`` is the AMD CPU performance scaling driver that introduces a17new CPU frequency control mechanism on modern AMD APU and CPU series in18Linux kernel. The new mechanism is based on Collaborative Processor19Performance Control (CPPC) which provides finer grain frequency management20than legacy ACPI hardware P-States. Current AMD CPU/APU platforms are using21the ACPI P-states driver to manage CPU frequency and clocks with switching22only in 3 P-states. CPPC replaces the ACPI P-states controls and allows a23flexible, low-latency interface for the Linux kernel to directly24communicate the performance hints to hardware.25 26``amd-pstate`` leverages the Linux kernel governors such as ``schedutil``,27``ondemand``, etc. to manage the performance hints which are provided by28CPPC hardware functionality that internally follows the hardware29specification (for details refer to AMD64 Architecture Programmer's Manual30Volume 2: System Programming [1]_). Currently, ``amd-pstate`` supports basic31frequency control function according to kernel governors on some of the32Zen2 and Zen3 processors, and we will implement more AMD specific functions33in future after we verify them on the hardware and SBIOS.34 35 36AMD CPPC Overview37=======================38 39Collaborative Processor Performance Control (CPPC) interface enumerates a40continuous, abstract, and unit-less performance value in a scale that is41not tied to a specific performance state / frequency. This is an ACPI42standard [2]_ which software can specify application performance goals and43hints as a relative target to the infrastructure limits. AMD processors44provide the low latency register model (MSR) instead of an AML code45interpreter for performance adjustments. ``amd-pstate`` will initialize a46``struct cpufreq_driver`` instance, ``amd_pstate_driver``, with the callbacks47to manage each performance update behavior. ::48 49 Highest Perf ------>+-----------------------+ +-----------------------+50 | | | |51 | | | |52 | | Max Perf ---->| |53 | | | |54 | | | |55 Nominal Perf ------>+-----------------------+ +-----------------------+56 | | | |57 | | | |58 | | | |59 | | | |60 | | | |61 | | | |62 | | Desired Perf ---->| |63 | | | |64 | | | |65 | | | |66 | | | |67 | | | |68 | | | |69 | | | |70 | | | |71 | | | |72 Lowest non- | | | |73 linear perf ------>+-----------------------+ +-----------------------+74 | | | |75 | | Lowest perf ---->| |76 | | | |77 Lowest perf ------>+-----------------------+ +-----------------------+78 | | | |79 | | | |80 | | | |81 0 ------>+-----------------------+ +-----------------------+82 83 AMD P-States Performance Scale84 85 86.. _perf_cap:87 88AMD CPPC Performance Capability89--------------------------------90 91Highest Performance (RO)92.........................93 94This is the absolute maximum performance an individual processor may reach,95assuming ideal conditions. This performance level may not be sustainable96for long durations and may only be achievable if other platform components97are in a specific state; for example, it may require other processors to be in98an idle state. This would be equivalent to the highest frequencies99supported by the processor.100 101Nominal (Guaranteed) Performance (RO)102......................................103 104This is the maximum sustained performance level of the processor, assuming105ideal operating conditions. In the absence of an external constraint (power,106thermal, etc.), this is the performance level the processor is expected to107be able to maintain continuously. All cores/processors are expected to be108able to sustain their nominal performance state simultaneously.109 110Lowest non-linear Performance (RO)111...................................112 113This is the lowest performance level at which nonlinear power savings are114achieved, for example, due to the combined effects of voltage and frequency115scaling. Above this threshold, lower performance levels should be generally116more energy efficient than higher performance levels. This register117effectively conveys the most efficient performance level to ``amd-pstate``.118 119Lowest Performance (RO)120........................121 122This is the absolute lowest performance level of the processor. Selecting a123performance level lower than the lowest nonlinear performance level may124cause an efficiency penalty but should reduce the instantaneous power125consumption of the processor.126 127AMD CPPC Performance Control128------------------------------129 130``amd-pstate`` passes performance goals through these registers. The131register drives the behavior of the desired performance target.132 133Minimum requested performance (RW)134...................................135 136``amd-pstate`` specifies the minimum allowed performance level.137 138Maximum requested performance (RW)139...................................140 141``amd-pstate`` specifies a limit the maximum performance that is expected142to be supplied by the hardware.143 144Desired performance target (RW)145...................................146 147``amd-pstate`` specifies a desired target in the CPPC performance scale as148a relative number. This can be expressed as percentage of nominal149performance (infrastructure max). Below the nominal sustained performance150level, desired performance expresses the average performance level of the151processor subject to hardware. Above the nominal performance level,152the processor must provide at least nominal performance requested and go higher153if current operating conditions allow.154 155Energy Performance Preference (EPP) (RW)156.........................................157 158This attribute provides a hint to the hardware if software wants to bias159toward performance (0x0) or energy efficiency (0xff).160 161 162Key Governors Support163=======================164 165``amd-pstate`` can be used with all the (generic) scaling governors listed166by the ``scaling_available_governors`` policy attribute in ``sysfs``. Then,167it is responsible for the configuration of policy objects corresponding to168CPUs and provides the ``CPUFreq`` core (and the scaling governors attached169to the policy objects) with accurate information on the maximum and minimum170operating frequencies supported by the hardware. Users can check the171``scaling_cur_freq`` information comes from the ``CPUFreq`` core.172 173``amd-pstate`` mainly supports ``schedutil`` and ``ondemand`` for dynamic174frequency control. It is to fine tune the processor configuration on175``amd-pstate`` to the ``schedutil`` with CPU CFS scheduler. ``amd-pstate``176registers the adjust_perf callback to implement performance update behavior177similar to CPPC. It is initialized by ``sugov_start`` and then populates the178CPU's update_util_data pointer to assign ``sugov_update_single_perf`` as the179utilization update callback function in the CPU scheduler. The CPU scheduler180will call ``cpufreq_update_util`` and assigns the target performance according181to the ``struct sugov_cpu`` that the utilization update belongs to.182Then, ``amd-pstate`` updates the desired performance according to the CPU183scheduler assigned.184 185.. _processor_support:186 187Processor Support188=======================189 190The ``amd-pstate`` initialization will fail if the ``_CPC`` entry in the ACPI191SBIOS does not exist in the detected processor. It uses ``acpi_cpc_valid``192to check the existence of ``_CPC``. All Zen based processors support the legacy193ACPI hardware P-States function, so when ``amd-pstate`` fails initialization,194the kernel will fall back to initialize the ``acpi-cpufreq`` driver.195 196There are two types of hardware implementations for ``amd-pstate``: one is197`Full MSR Support <perf_cap_>`_ and another is `Shared Memory Support198<perf_cap_>`_. It can use the :c:macro:`X86_FEATURE_CPPC` feature flag to199indicate the different types. (For details, refer to the Processor Programming200Reference (PPR) for AMD Family 19h Model 51h, Revision A1 Processors [3]_.)201``amd-pstate`` is to register different ``static_call`` instances for different202hardware implementations.203 204Currently, some of the Zen2 and Zen3 processors support ``amd-pstate``. In the205future, it will be supported on more and more AMD processors.206 207Full MSR Support208-----------------209 210Some new Zen3 processors such as Cezanne provide the MSR registers directly211while the :c:macro:`X86_FEATURE_CPPC` CPU feature flag is set.212``amd-pstate`` can handle the MSR register to implement the fast switch213function in ``CPUFreq`` that can reduce the latency of frequency control in214interrupt context. The functions with a ``pstate_xxx`` prefix represent the215operations on MSR registers.216 217Shared Memory Support218----------------------219 220If the :c:macro:`X86_FEATURE_CPPC` CPU feature flag is not set, the221processor supports the shared memory solution. In this case, ``amd-pstate``222uses the ``cppc_acpi`` helper methods to implement the callback functions223that are defined on ``static_call``. The functions with the ``cppc_xxx`` prefix224represent the operations of ACPI CPPC helpers for the shared memory solution.225 226 227AMD P-States and ACPI hardware P-States always can be supported in one228processor. But AMD P-States has the higher priority and if it is enabled229with :c:macro:`MSR_AMD_CPPC_ENABLE` or ``cppc_set_enable``, it will respond230to the request from AMD P-States.231 232 233User Space Interface in ``sysfs`` - Per-policy control234======================================================235 236``amd-pstate`` exposes several global attributes (files) in ``sysfs`` to237control its functionality at the system level. They are located in the238``/sys/devices/system/cpu/cpufreq/policyX/`` directory and affect all CPUs. ::239 240 root@hr-test1:/home/ray# ls /sys/devices/system/cpu/cpufreq/policy0/*amd*241 /sys/devices/system/cpu/cpufreq/policy0/amd_pstate_highest_perf242 /sys/devices/system/cpu/cpufreq/policy0/amd_pstate_lowest_nonlinear_freq243 /sys/devices/system/cpu/cpufreq/policy0/amd_pstate_max_freq244 245 246``amd_pstate_highest_perf / amd_pstate_max_freq``247 248Maximum CPPC performance and CPU frequency that the driver is allowed to249set, in percent of the maximum supported CPPC performance level (the highest250performance supported in `AMD CPPC Performance Capability <perf_cap_>`_).251In some ASICs, the highest CPPC performance is not the one in the ``_CPC``252table, so we need to expose it to sysfs. If boost is not active, but253still supported, this maximum frequency will be larger than the one in254``cpuinfo``. On systems that support preferred core, the driver will have255different values for some cores than others and this will reflect the values256advertised by the platform at bootup.257This attribute is read-only.258 259``amd_pstate_lowest_nonlinear_freq``260 261The lowest non-linear CPPC CPU frequency that the driver is allowed to set,262in percent of the maximum supported CPPC performance level. (Please see the263lowest non-linear performance in `AMD CPPC Performance Capability264<perf_cap_>`_.)265This attribute is read-only.266 267``amd_pstate_hw_prefcore``268 269Whether the platform supports the preferred core feature and it has been270enabled. This attribute is read-only.271 272``amd_pstate_prefcore_ranking``273 274The performance ranking of the core. This number doesn't have any unit, but275larger numbers are preferred at the time of reading. This can change at276runtime based on platform conditions. This attribute is read-only.277 278``energy_performance_available_preferences``279 280A list of all the supported EPP preferences that could be used for281``energy_performance_preference`` on this system.282These profiles represent different hints that are provided283to the low-level firmware about the user's desired energy vs efficiency284tradeoff. ``default`` represents the epp value is set by platform285firmware. This attribute is read-only.286 287``energy_performance_preference``288 289The current energy performance preference can be read from this attribute.290and user can change current preference according to energy or performance needs291Please get all support profiles list from292``energy_performance_available_preferences`` attribute, all the profiles are293integer values defined between 0 to 255 when EPP feature is enabled by platform294firmware, if EPP feature is disabled, driver will ignore the written value295This attribute is read-write.296 297``boost``298The `boost` sysfs attribute provides control over the CPU core299performance boost, allowing users to manage the maximum frequency limitation300of the CPU. This attribute can be used to enable or disable the boost feature301on individual CPUs.302 303When the boost feature is enabled, the CPU can dynamically increase its frequency304beyond the base frequency, providing enhanced performance for demanding workloads.305On the other hand, disabling the boost feature restricts the CPU to operate at the306base frequency, which may be desirable in certain scenarios to prioritize power307efficiency or manage temperature.308 309To manipulate the `boost` attribute, users can write a value of `0` to disable the310boost or `1` to enable it, for the respective CPU using the sysfs path311`/sys/devices/system/cpu/cpuX/cpufreq/boost`, where `X` represents the CPU number.312 313Other performance and frequency values can be read back from314``/sys/devices/system/cpu/cpuX/acpi_cppc/``, see :ref:`cppc_sysfs`.315 316 317``amd-pstate`` vs ``acpi-cpufreq``318======================================319 320On the majority of AMD platforms supported by ``acpi-cpufreq``, the ACPI tables321provided by the platform firmware are used for CPU performance scaling, but322only provide 3 P-states on AMD processors.323However, on modern AMD APU and CPU series, hardware provides the Collaborative324Processor Performance Control according to the ACPI protocol and customizes this325for AMD platforms. That is, fine-grained and continuous frequency ranges326instead of the legacy hardware P-states. ``amd-pstate`` is the kernel327module which supports the new AMD P-States mechanism on most of the future AMD328platforms. The AMD P-States mechanism is the more performance and energy329efficiency frequency management method on AMD processors.330 331 332``amd-pstate`` Driver Operation Modes333======================================334 335``amd_pstate`` CPPC has 3 operation modes: autonomous (active) mode,336non-autonomous (passive) mode and guided autonomous (guided) mode.337Active/passive/guided mode can be chosen by different kernel parameters.338 339- In autonomous mode, platform ignores the desired performance level request340 and takes into account only the values set to the minimum, maximum and energy341 performance preference registers.342- In non-autonomous mode, platform gets desired performance level343 from OS directly through Desired Performance Register.344- In guided-autonomous mode, platform sets operating performance level345 autonomously according to the current workload and within the limits set by346 OS through min and max performance registers.347 348Active Mode349------------350 351``amd_pstate=active``352 353This is the low-level firmware control mode which is implemented by ``amd_pstate_epp``354driver with ``amd_pstate=active`` passed to the kernel in the command line.355In this mode, ``amd_pstate_epp`` driver provides a hint to the hardware if software356wants to bias toward performance (0x0) or energy efficiency (0xff) to the CPPC firmware.357then CPPC power algorithm will calculate the runtime workload and adjust the realtime358cores frequency according to the power supply and thermal, core voltage and some other359hardware conditions.360 361Passive Mode362------------363 364``amd_pstate=passive``365 366It will be enabled if the ``amd_pstate=passive`` is passed to the kernel in the command line.367In this mode, ``amd_pstate`` driver software specifies a desired QoS target in the CPPC368performance scale as a relative number. This can be expressed as percentage of nominal369performance (infrastructure max). Below the nominal sustained performance level,370desired performance expresses the average performance level of the processor subject371to the Performance Reduction Tolerance register. Above the nominal performance level,372processor must provide at least nominal performance requested and go higher if current373operating conditions allow.374 375Guided Mode376-----------377 378``amd_pstate=guided``379 380If ``amd_pstate=guided`` is passed to kernel command line option then this mode381is activated. In this mode, driver requests minimum and maximum performance382level and the platform autonomously selects a performance level in this range383and appropriate to the current workload.384 385``amd-pstate`` Preferred Core386=================================387 388The core frequency is subjected to the process variation in semiconductors.389Not all cores are able to reach the maximum frequency respecting the390infrastructure limits. Consequently, AMD has redefined the concept of391maximum frequency of a part. This means that a fraction of cores can reach392maximum frequency. To find the best process scheduling policy for a given393scenario, OS needs to know the core ordering informed by the platform through394highest performance capability register of the CPPC interface.395 396``amd-pstate`` preferred core enables the scheduler to prefer scheduling on397cores that can achieve a higher frequency with lower voltage. The preferred398core rankings can dynamically change based on the workload, platform conditions,399thermals and ageing.400 401The priority metric will be initialized by the ``amd-pstate`` driver. The ``amd-pstate``402driver will also determine whether or not ``amd-pstate`` preferred core is403supported by the platform.404 405``amd-pstate`` driver will provide an initial core ordering when the system boots.406The platform uses the CPPC interfaces to communicate the core ranking to the407operating system and scheduler to make sure that OS is choosing the cores408with highest performance firstly for scheduling the process. When ``amd-pstate``409driver receives a message with the highest performance change, it will410update the core ranking and set the cpu's priority.411 412``amd-pstate`` Preferred Core Switch413=====================================414Kernel Parameters415-----------------416 417``amd-pstate`` peferred core`` has two states: enable and disable.418Enable/disable states can be chosen by different kernel parameters.419Default enable ``amd-pstate`` preferred core.420 421``amd_prefcore=disable``422 423For systems that support ``amd-pstate`` preferred core, the core rankings will424always be advertised by the platform. But OS can choose to ignore that via the425kernel parameter ``amd_prefcore=disable``.426 427User Space Interface in ``sysfs`` - General428===========================================429 430Global Attributes431-----------------432 433``amd-pstate`` exposes several global attributes (files) in ``sysfs`` to434control its functionality at the system level. They are located in the435``/sys/devices/system/cpu/amd_pstate/`` directory and affect all CPUs.436 437``status``438 Operation mode of the driver: "active", "passive", "guided" or "disable".439 440 "active"441 The driver is functional and in the ``active mode``442 443 "passive"444 The driver is functional and in the ``passive mode``445 446 "guided"447 The driver is functional and in the ``guided mode``448 449 "disable"450 The driver is unregistered and not functional now.451 452 This attribute can be written to in order to change the driver's453 operation mode or to unregister it. The string written to it must be454 one of the possible values of it and, if successful, writing one of455 these values to the sysfs file will cause the driver to switch over456 to the operation mode represented by that string - or to be457 unregistered in the "disable" case.458 459``prefcore``460 Preferred core state of the driver: "enabled" or "disabled".461 462 "enabled"463 Enable the ``amd-pstate`` preferred core.464 465 "disabled"466 Disable the ``amd-pstate`` preferred core467 468 469 This attribute is read-only to check the state of preferred core set470 by the kernel parameter.471 472``cpupower`` tool support for ``amd-pstate``473===============================================474 475``amd-pstate`` is supported by the ``cpupower`` tool, which can be used to dump476frequency information. Development is in progress to support more and more477operations for the new ``amd-pstate`` module with this tool. ::478 479 root@hr-test1:/home/ray# cpupower frequency-info480 analyzing CPU 0:481 driver: amd-pstate482 CPUs which run at the same hardware frequency: 0483 CPUs which need to have their frequency coordinated by software: 0484 maximum transition latency: 131 us485 hardware limits: 400 MHz - 4.68 GHz486 available cpufreq governors: ondemand conservative powersave userspace performance schedutil487 current policy: frequency should be within 400 MHz and 4.68 GHz.488 The governor "schedutil" may decide which speed to use489 within this range.490 current CPU frequency: Unable to call hardware491 current CPU frequency: 4.02 GHz (asserted by call to kernel)492 boost state support:493 Supported: yes494 Active: yes495 AMD PSTATE Highest Performance: 166. Maximum Frequency: 4.68 GHz.496 AMD PSTATE Nominal Performance: 117. Nominal Frequency: 3.30 GHz.497 AMD PSTATE Lowest Non-linear Performance: 39. Lowest Non-linear Frequency: 1.10 GHz.498 AMD PSTATE Lowest Performance: 15. Lowest Frequency: 400 MHz.499 500 501Diagnostics and Tuning502=======================503 504Trace Events505--------------506 507There are two static trace events that can be used for ``amd-pstate``508diagnostics. One of them is the ``cpu_frequency`` trace event generally used509by ``CPUFreq``, and the other one is the ``amd_pstate_perf`` trace event510specific to ``amd-pstate``. The following sequence of shell commands can511be used to enable them and see their output (if the kernel is512configured to support event tracing). ::513 514 root@hr-test1:/home/ray# cd /sys/kernel/tracing/515 root@hr-test1:/sys/kernel/tracing# echo 1 > events/amd_cpu/enable516 root@hr-test1:/sys/kernel/tracing# cat trace517 # tracer: nop518 #519 # entries-in-buffer/entries-written: 47827/42233061 #P:2520 #521 # _-----=> irqs-off522 # / _----=> need-resched523 # | / _---=> hardirq/softirq524 # || / _--=> preempt-depth525 # ||| / delay526 # TASK-PID CPU# |||| TIMESTAMP FUNCTION527 # | | | |||| | |528 <idle>-0 [015] dN... 4995.979886: amd_pstate_perf: amd_min_perf=85 amd_des_perf=85 amd_max_perf=166 cpu_id=15 changed=false fast_switch=true529 <idle>-0 [007] d.h.. 4995.979893: amd_pstate_perf: amd_min_perf=85 amd_des_perf=85 amd_max_perf=166 cpu_id=7 changed=false fast_switch=true530 cat-2161 [000] d.... 4995.980841: amd_pstate_perf: amd_min_perf=85 amd_des_perf=85 amd_max_perf=166 cpu_id=0 changed=false fast_switch=true531 sshd-2125 [004] d.s.. 4995.980968: amd_pstate_perf: amd_min_perf=85 amd_des_perf=85 amd_max_perf=166 cpu_id=4 changed=false fast_switch=true532 <idle>-0 [007] d.s.. 4995.980968: amd_pstate_perf: amd_min_perf=85 amd_des_perf=85 amd_max_perf=166 cpu_id=7 changed=false fast_switch=true533 <idle>-0 [003] d.s.. 4995.980971: amd_pstate_perf: amd_min_perf=85 amd_des_perf=85 amd_max_perf=166 cpu_id=3 changed=false fast_switch=true534 <idle>-0 [011] d.s.. 4995.980996: amd_pstate_perf: amd_min_perf=85 amd_des_perf=85 amd_max_perf=166 cpu_id=11 changed=false fast_switch=true535 536The ``cpu_frequency`` trace event will be triggered either by the ``schedutil`` scaling537governor (for the policies it is attached to), or by the ``CPUFreq`` core (for the538policies with other scaling governors).539 540 541Tracer Tool542-------------543 544``amd_pstate_tracer.py`` can record and parse ``amd-pstate`` trace log, then545generate performance plots. This utility can be used to debug and tune the546performance of ``amd-pstate`` driver. The tracer tool needs to import intel547pstate tracer.548 549Tracer tool located in ``linux/tools/power/x86/amd_pstate_tracer``. It can be550used in two ways. If trace file is available, then directly parse the file551with command ::552 553 ./amd_pstate_trace.py [-c cpus] -t <trace_file> -n <test_name>554 555Or generate trace file with root privilege, then parse and plot with command ::556 557 sudo ./amd_pstate_trace.py [-c cpus] -n <test_name> -i <interval> [-m kbytes]558 559The test result can be found in ``results/test_name``. Following is the example560about part of the output. ::561 562 common_cpu common_secs common_usecs min_perf des_perf max_perf freq mperf apef tsc load duration_ms sample_num elapsed_time common_comm563 CPU_005 712 116384 39 49 166 0.7565 9645075 2214891 38431470 25.1 11.646 469 2.496 kworker/5:0-40564 CPU_006 712 116408 39 49 166 0.6769 8950227 1839034 37192089 24.06 11.272 470 2.496 kworker/6:0-1264565 566Unit Tests for amd-pstate567-------------------------568 569``amd-pstate-ut`` is a test module for testing the ``amd-pstate`` driver.570 571 * It can help all users to verify their processor support (SBIOS/Firmware or Hardware).572 573 * Kernel can have a basic function test to avoid the kernel regression during the update.574 575 * We can introduce more functional or performance tests to align the result together, it will benefit power and performance scale optimization.576 5771. Test case descriptions578 579 1). Basic tests580 581 Test prerequisite and basic functions for the ``amd-pstate`` driver.582 583 +---------+--------------------------------+------------------------------------------------------------------------------------+584 | Index | Functions | Description |585 +=========+================================+====================================================================================+586 | 1 | amd_pstate_ut_acpi_cpc_valid || Check whether the _CPC object is present in SBIOS. |587 | | || |588 | | || The detail refer to `Processor Support <processor_support_>`_. |589 +---------+--------------------------------+------------------------------------------------------------------------------------+590 | 2 | amd_pstate_ut_check_enabled || Check whether AMD P-State is enabled. |591 | | || |592 | | || AMD P-States and ACPI hardware P-States always can be supported in one processor. |593 | | | But AMD P-States has the higher priority and if it is enabled with |594 | | | :c:macro:`MSR_AMD_CPPC_ENABLE` or ``cppc_set_enable``, it will respond to the |595 | | | request from AMD P-States. |596 +---------+--------------------------------+------------------------------------------------------------------------------------+597 | 3 | amd_pstate_ut_check_perf || Check if the each performance values are reasonable. |598 | | || highest_perf >= nominal_perf > lowest_nonlinear_perf > lowest_perf > 0. |599 +---------+--------------------------------+------------------------------------------------------------------------------------+600 | 4 | amd_pstate_ut_check_freq || Check if the each frequency values and max freq when set support boost mode |601 | | | are reasonable. |602 | | || max_freq >= nominal_freq > lowest_nonlinear_freq > min_freq > 0 |603 | | || If boost is not active but supported, this maximum frequency will be larger than |604 | | | the one in ``cpuinfo``. |605 +---------+--------------------------------+------------------------------------------------------------------------------------+606 607 2). Tbench test608 609 Test and monitor the cpu changes when running tbench benchmark under the specified governor.610 These changes include desire performance, frequency, load, performance, energy etc.611 The specified governor is ondemand or schedutil.612 Tbench can also be tested on the ``acpi-cpufreq`` kernel driver for comparison.613 614 3). Gitsource test615 616 Test and monitor the cpu changes when running gitsource benchmark under the specified governor.617 These changes include desire performance, frequency, load, time, energy etc.618 The specified governor is ondemand or schedutil.619 Gitsource can also be tested on the ``acpi-cpufreq`` kernel driver for comparison.620 621#. How to execute the tests622 623 We use test module in the kselftest frameworks to implement it.624 We create ``amd-pstate-ut`` module and tie it into kselftest.(for625 details refer to Linux Kernel Selftests [4]_).626 627 1). Build628 629 + open the :c:macro:`CONFIG_X86_AMD_PSTATE` configuration option.630 + set the :c:macro:`CONFIG_X86_AMD_PSTATE_UT` configuration option to M.631 + make project632 + make selftest ::633 634 $ cd linux635 $ make -C tools/testing/selftests636 637 + make perf ::638 639 $ cd tools/perf/640 $ make641 642 643 2). Installation & Steps ::644 645 $ make -C tools/testing/selftests install INSTALL_PATH=~/kselftest646 $ cp tools/perf/perf /usr/bin/perf647 $ sudo ./kselftest/run_kselftest.sh -c amd-pstate648 649 3). Specified test case ::650 651 $ cd ~/kselftest/amd-pstate652 $ sudo ./run.sh -t basic653 $ sudo ./run.sh -t tbench654 $ sudo ./run.sh -t tbench -m acpi-cpufreq655 $ sudo ./run.sh -t gitsource656 $ sudo ./run.sh -t gitsource -m acpi-cpufreq657 $ ./run.sh --help658 ./run.sh: illegal option -- -659 Usage: ./run.sh [OPTION...]660 [-h <help>]661 [-o <output-file-for-dump>]662 [-c <all: All testing,663 basic: Basic testing,664 tbench: Tbench testing,665 gitsource: Gitsource testing.>]666 [-t <tbench time limit>]667 [-p <tbench process number>]668 [-l <loop times for tbench>]669 [-i <amd tracer interval>]670 [-m <comparative test: acpi-cpufreq>]671 672 673 4). Results674 675 + basic676 677 When you finish test, you will get the following log info ::678 679 $ dmesg | grep "amd_pstate_ut" | tee log.txt680 [12977.570663] amd_pstate_ut: 1 amd_pstate_ut_acpi_cpc_valid success!681 [12977.570673] amd_pstate_ut: 2 amd_pstate_ut_check_enabled success!682 [12977.571207] amd_pstate_ut: 3 amd_pstate_ut_check_perf success!683 [12977.571212] amd_pstate_ut: 4 amd_pstate_ut_check_freq success!684 685 + tbench686 687 When you finish test, you will get selftest.tbench.csv and png images.688 The selftest.tbench.csv file contains the raw data and the drop of the comparative test.689 The png images shows the performance, energy and performan per watt of each test.690 Open selftest.tbench.csv :691 692 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+693 + Governor | Round | Des-perf | Freq | Load | Performance | Energy | Performance Per Watt |694 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+695 + Unit | | | GHz | | MB/s | J | MB/J |696 +=================================================+==============+==========+=========+==========+=============+=========+======================+697 + amd-pstate-ondemand | 1 | | | | 2504.05 | 1563.67 | 158.5378 |698 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+699 + amd-pstate-ondemand | 2 | | | | 2243.64 | 1430.32 | 155.2941 |700 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+701 + amd-pstate-ondemand | 3 | | | | 2183.88 | 1401.32 | 154.2860 |702 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+703 + amd-pstate-ondemand | Average | | | | 2310.52 | 1465.1 | 156.1268 |704 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+705 + amd-pstate-schedutil | 1 | 165.329 | 1.62257 | 99.798 | 2136.54 | 1395.26 | 151.5971 |706 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+707 + amd-pstate-schedutil | 2 | 166 | 1.49761 | 99.9993 | 2100.56 | 1380.5 | 150.6377 |708 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+709 + amd-pstate-schedutil | 3 | 166 | 1.47806 | 99.9993 | 2084.12 | 1375.76 | 149.9737 |710 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+711 + amd-pstate-schedutil | Average | 165.776 | 1.53275 | 99.9322 | 2107.07 | 1383.84 | 150.7399 |712 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+713 + acpi-cpufreq-ondemand | 1 | | | | 2529.9 | 1564.4 | 160.0997 |714 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+715 + acpi-cpufreq-ondemand | 2 | | | | 2249.76 | 1432.97 | 155.4297 |716 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+717 + acpi-cpufreq-ondemand | 3 | | | | 2181.46 | 1406.88 | 153.5060 |718 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+719 + acpi-cpufreq-ondemand | Average | | | | 2320.37 | 1468.08 | 156.4741 |720 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+721 + acpi-cpufreq-schedutil | 1 | | | | 2137.64 | 1385.24 | 152.7723 |722 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+723 + acpi-cpufreq-schedutil | 2 | | | | 2107.05 | 1372.23 | 152.0138 |724 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+725 + acpi-cpufreq-schedutil | 3 | | | | 2085.86 | 1365.35 | 151.2433 |726 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+727 + acpi-cpufreq-schedutil | Average | | | | 2110.18 | 1374.27 | 152.0136 |728 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+729 + acpi-cpufreq-ondemand VS acpi-cpufreq-schedutil | Comprison(%) | | | | -9.0584 | -6.3899 | -2.8506 |730 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+731 + amd-pstate-ondemand VS amd-pstate-schedutil | Comprison(%) | | | | 8.8053 | -5.5463 | -3.4503 |732 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+733 + acpi-cpufreq-ondemand VS amd-pstate-ondemand | Comprison(%) | | | | -0.4245 | -0.2029 | -0.2219 |734 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+735 + acpi-cpufreq-schedutil VS amd-pstate-schedutil | Comprison(%) | | | | -0.1473 | 0.6963 | -0.8378 |736 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+737 738 + gitsource739 740 When you finish test, you will get selftest.gitsource.csv and png images.741 The selftest.gitsource.csv file contains the raw data and the drop of the comparative test.742 The png images shows the performance, energy and performan per watt of each test.743 Open selftest.gitsource.csv :744 745 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+746 + Governor | Round | Des-perf | Freq | Load | Time | Energy | Performance Per Watt |747 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+748 + Unit | | | GHz | | s | J | 1/J |749 +=================================================+==============+==========+==========+==========+=============+=========+======================+750 + amd-pstate-ondemand | 1 | 50.119 | 2.10509 | 23.3076 | 475.69 | 865.78 | 0.001155027 |751 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+752 + amd-pstate-ondemand | 2 | 94.8006 | 1.98771 | 56.6533 | 467.1 | 839.67 | 0.001190944 |753 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+754 + amd-pstate-ondemand | 3 | 76.6091 | 2.53251 | 43.7791 | 467.69 | 855.85 | 0.001168429 |755 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+756 + amd-pstate-ondemand | Average | 73.8429 | 2.20844 | 41.2467 | 470.16 | 853.767 | 0.001171279 |757 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+758 + amd-pstate-schedutil | 1 | 165.919 | 1.62319 | 98.3868 | 464.17 | 866.8 | 0.001153668 |759 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+760 + amd-pstate-schedutil | 2 | 165.97 | 1.31309 | 99.5712 | 480.15 | 880.4 | 0.001135847 |761 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+762 + amd-pstate-schedutil | 3 | 165.973 | 1.28448 | 99.9252 | 481.79 | 867.02 | 0.001153375 |763 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+764 + amd-pstate-schedutil | Average | 165.954 | 1.40692 | 99.2944 | 475.37 | 871.407 | 0.001147569 |765 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+766 + acpi-cpufreq-ondemand | 1 | | | | 2379.62 | 742.96 | 0.001345967 |767 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+768 + acpi-cpufreq-ondemand | 2 | | | | 441.74 | 817.49 | 0.001223256 |769 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+770 + acpi-cpufreq-ondemand | 3 | | | | 455.48 | 820.01 | 0.001219497 |771 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+772 + acpi-cpufreq-ondemand | Average | | | | 425.613 | 793.487 | 0.001260260 |773 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+774 + acpi-cpufreq-schedutil | 1 | | | | 459.69 | 838.54 | 0.001192548 |775 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+776 + acpi-cpufreq-schedutil | 2 | | | | 466.55 | 830.89 | 0.001203528 |777 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+778 + acpi-cpufreq-schedutil | 3 | | | | 470.38 | 837.32 | 0.001194286 |779 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+780 + acpi-cpufreq-schedutil | Average | | | | 465.54 | 835.583 | 0.001196769 |781 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+782 + acpi-cpufreq-ondemand VS acpi-cpufreq-schedutil | Comprison(%) | | | | 9.3810 | 5.3051 | -5.0379 |783 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+784 + amd-pstate-ondemand VS amd-pstate-schedutil | Comprison(%) | 124.7392 | -36.2934 | 140.7329 | 1.1081 | 2.0661 | -2.0242 |785 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+786 + acpi-cpufreq-ondemand VS amd-pstate-ondemand | Comprison(%) | | | | 10.4665 | 7.5968 | -7.0605 |787 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+788 + acpi-cpufreq-schedutil VS amd-pstate-schedutil | Comprison(%) | | | | 2.1115 | 4.2873 | -4.1110 |789 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+790 791Reference792===========793 794.. [1] AMD64 Architecture Programmer's Manual Volume 2: System Programming,795 https://www.amd.com/system/files/TechDocs/24593.pdf796 797.. [2] Advanced Configuration and Power Interface Specification,798 https://uefi.org/sites/default/files/resources/ACPI_Spec_6_4_Jan22.pdf799 800.. [3] Processor Programming Reference (PPR) for AMD Family 19h Model 51h, Revision A1 Processors801 https://www.amd.com/system/files/TechDocs/56569-A1-PUB.zip802 803.. [4] Linux Kernel Selftests,804 https://www.kernel.org/doc/html/latest/dev-tools/kselftest.html805