amd-pstate CPU Performance Scaling Driver

Copyright:

© 2021 Advanced Micro Devices, Inc.

Author:

Huang Rui <ray.huang@amd.com>

Introduction

amd-pstate is the AMD CPU performance scaling driver that introduces anew CPU frequency control mechanism on modern AMD APU and CPU series inLinux kernel. The new mechanism is based on Collaborative ProcessorPerformance Control (CPPC) which provides finer grain frequency managementthan legacy ACPI hardware P-States. Current AMD CPU/APU platforms are usingthe ACPI P-states driver to manage CPU frequency and clocks with switchingonly in 3 P-states. CPPC replaces the ACPI P-states controls and allows aflexible, low-latency interface for the Linux kernel to directlycommunicate the performance hints to hardware.

amd-pstate leverages the Linux kernel governors such asschedutil,ondemand, etc. to manage the performance hints which are provided byCPPC hardware functionality that internally follows the hardwarespecification (for details refer to AMD64 Architecture Programmer’s ManualVolume 2: System Programming[1]). Currently,amd-pstate supports basicfrequency control function according to kernel governors on some of theZen2 and Zen3 processors, and we will implement more AMD specific functionsin future after we verify them on the hardware and SBIOS.

AMD CPPC Overview

Collaborative Processor Performance Control (CPPC) interface enumerates acontinuous, abstract, and unit-less performance value in a scale that isnot tied to a specific performance state / frequency. This is an ACPIstandard[2] which software can specify application performance goals andhints as a relative target to the infrastructure limits. AMD processorsprovide the low latency register model (MSR) instead of an AML codeinterpreter for performance adjustments.amd-pstate will initialize astructcpufreq_driver instance,amd_pstate_driver, with the callbacksto manage each performance update behavior.

Highest Perf ------>+-----------------------+                         +-----------------------+                    |                       |                         |                       |                    |                       |                         |                       |                    |                       |          Max Perf  ---->|                       |                    |                       |                         |                       |                    |                       |                         |                       |Nominal Perf ------>+-----------------------+                         +-----------------------+                    |                       |                         |                       |                    |                       |                         |                       |                    |                       |                         |                       |                    |                       |                         |                       |                    |                       |                         |                       |                    |                       |                         |                       |                    |                       |      Desired Perf  ---->|                       |                    |                       |                         |                       |                    |                       |                         |                       |                    |                       |                         |                       |                    |                       |                         |                       |                    |                       |                         |                       |                    |                       |                         |                       |                    |                       |                         |                       |                    |                       |                         |                       |                    |                       |                         |                       | Lowest non-        |                       |                         |                       | linear perf ------>+-----------------------+                         +-----------------------+                    |                       |                         |                       |                    |                       |       Lowest perf  ---->|                       |                    |                       |                         |                       | Lowest perf ------>+-----------------------+                         +-----------------------+                    |                       |                         |                       |                    |                       |                         |                       |                    |                       |                         |                       |         0   ------>+-----------------------+                         +-----------------------+                                    AMD P-States Performance Scale

AMD CPPC Performance Capability

Highest Performance (RO)

This is the absolute maximum performance an individual processor may reach,assuming ideal conditions. This performance level may not be sustainablefor long durations and may only be achievable if other platform componentsare in a specific state; for example, it may require other processors to be inan idle state. This would be equivalent to the highest frequenciessupported by the processor.

Nominal (Guaranteed) Performance (RO)

This is the maximum sustained performance level of the processor, assumingideal operating conditions. In the absence of an external constraint (power,thermal, etc.), this is the performance level the processor is expected tobe able to maintain continuously. All cores/processors are expected to beable to sustain their nominal performance state simultaneously.

Lowest non-linear Performance (RO)

This is the lowest performance level at which nonlinear power savings areachieved, for example, due to the combined effects of voltage and frequencyscaling. Above this threshold, lower performance levels should be generallymore energy efficient than higher performance levels. This registereffectively conveys the most efficient performance level toamd-pstate.

Lowest Performance (RO)

This is the absolute lowest performance level of the processor. Selecting aperformance level lower than the lowest nonlinear performance level maycause an efficiency penalty but should reduce the instantaneous powerconsumption of the processor.

AMD CPPC Performance Control

amd-pstate passes performance goals through these registers. Theregister drives the behavior of the desired performance target.

Minimum requested performance (RW)

amd-pstate specifies the minimum allowed performance level.

Maximum requested performance (RW)

amd-pstate specifies a limit the maximum performance that is expectedto be supplied by the hardware.

Desired performance target (RW)

amd-pstate specifies a desired target in the CPPC performance scale asa relative number. This can be expressed as percentage of nominalperformance (infrastructure max). Below the nominal sustained performancelevel, desired performance expresses the average performance level of theprocessor subject to hardware. Above the nominal performance level,the processor must provide at least nominal performance requested and go higherif current operating conditions allow.

Energy Performance Preference (EPP) (RW)

This attribute provides a hint to the hardware if software wants to biastoward performance (0x0) or energy efficiency (0xff).

Key Governors Support

amd-pstate can be used with all the (generic) scaling governors listedby thescaling_available_governors policy attribute insysfs. Then,it is responsible for the configuration of policy objects corresponding toCPUs and provides theCPUFreq core (and the scaling governors attachedto the policy objects) with accurate information on the maximum and minimumoperating frequencies supported by the hardware. Users can check thescaling_cur_freq information comes from theCPUFreq core.

amd-pstate mainly supportsschedutil andondemand for dynamicfrequency control. It is to fine tune the processor configuration onamd-pstate to theschedutil with CPU CFS scheduler.amd-pstateregisters the adjust_perf callback to implement performance update behaviorsimilar to CPPC. It is initialized bysugov_start and then populates theCPU’s update_util_data pointer to assignsugov_update_single_perf as theutilization update callback function in the CPU scheduler. The CPU schedulerwill callcpufreq_update_util and assigns the target performance accordingto thestructsugov_cpu that the utilization update belongs to.Then,amd-pstate updates the desired performance according to the CPUscheduler assigned.

Processor Support

Theamd-pstate initialization will fail if the_CPC entry in the ACPISBIOS does not exist in the detected processor. It usesacpi_cpc_validto check the existence of_CPC. All Zen based processors support the legacyACPI hardware P-States function, so whenamd-pstate fails initialization,the kernel will fall back to initialize theacpi-cpufreq driver.

There are two types of hardware implementations foramd-pstate: one isFull MSR Support and another isShared Memory Support. It can use theX86_FEATURE_CPPC feature flag toindicate the different types. (For details, refer to the Processor ProgrammingReference (PPR) for AMD Family 19h Model 51h, Revision A1 Processors[3].)amd-pstate is to register differentstatic_call instances for differenthardware implementations.

Currently, some of the Zen2 and Zen3 processors supportamd-pstate. In thefuture, it will be supported on more and more AMD processors.

Full MSR Support

Some new Zen3 processors such as Cezanne provide the MSR registers directlywhile theX86_FEATURE_CPPC CPU feature flag is set.amd-pstate can handle the MSR register to implement the fast switchfunction inCPUFreq that can reduce the latency of frequency control ininterrupt context. The functions with apstate_xxx prefix represent theoperations on MSR registers.

Shared Memory Support

If theX86_FEATURE_CPPC CPU feature flag is not set, theprocessor supports the shared memory solution. In this case,amd-pstateuses thecppc_acpi helper methods to implement the callback functionsthat are defined onstatic_call. The functions with thecppc_xxx prefixrepresent the operations of ACPI CPPC helpers for the shared memory solution.

AMD P-States and ACPI hardware P-States always can be supported in oneprocessor. But AMD P-States has the higher priority and if it is enabledwithMSR_AMD_CPPC_ENABLE orcppc_set_enable, it will respondto the request from AMD P-States.

User Space Interface insysfs - Per-policy control

amd-pstate exposes several global attributes (files) insysfs tocontrol its functionality at the system level. They are located in the/sys/devices/system/cpu/cpufreq/policyX/ directory and affect all CPUs.

root@hr-test1:/home/ray# ls /sys/devices/system/cpu/cpufreq/policy0/*amd*/sys/devices/system/cpu/cpufreq/policy0/amd_pstate_highest_perf/sys/devices/system/cpu/cpufreq/policy0/amd_pstate_lowest_nonlinear_freq/sys/devices/system/cpu/cpufreq/policy0/amd_pstate_max_freq

amd_pstate_highest_perf/amd_pstate_max_freq

Maximum CPPC performance and CPU frequency that the driver is allowed toset, in percent of the maximum supported CPPC performance level (the highestperformance supported inAMD CPPC Performance Capability).In some ASICs, the highest CPPC performance is not the one in the_CPCtable, so we need to expose it to sysfs. If boost is not active, butstill supported, this maximum frequency will be larger than the one incpuinfo.This attribute is read-only.

amd_pstate_lowest_nonlinear_freq

The lowest non-linear CPPC CPU frequency that the driver is allowed to set,in percent of the maximum supported CPPC performance level. (Please see thelowest non-linear performance inAMD CPPC Performance Capability.)This attribute is read-only.

amd_pstate_hw_prefcore

Whether the platform supports the preferred core feature and it has beenenabled. This attribute is read-only.

amd_pstate_prefcore_ranking

The performance ranking of the core. This number doesn’t have any unit, butlarger numbers are preferred at the time of reading. This can change atruntime based on platform conditions. This attribute is read-only.

energy_performance_available_preferences

A list of all the supported EPP preferences that could be used forenergy_performance_preference on this system.These profiles represent different hints that are providedto the low-level firmware about the user’s desired energy vs efficiencytradeoff.default represents the epp value is set by platformfirmware. This attribute is read-only.

energy_performance_preference

The current energy performance preference can be read from this attribute.and user can change current preference according to energy or performance needsPlease get all support profiles list fromenergy_performance_available_preferences attribute, all the profiles areinteger values defined between 0 to 255 when EPP feature is enabled by platformfirmware, if EPP feature is disabled, driver will ignore the written valueThis attribute is read-write.

boostTheboost sysfs attribute provides control over the CPU coreperformance boost, allowing users to manage the maximum frequency limitationof the CPU. This attribute can be used to enable or disable the boost featureon individual CPUs.

When the boost feature is enabled, the CPU can dynamically increase its frequencybeyond the base frequency, providing enhanced performance for demanding workloads.On the other hand, disabling the boost feature restricts the CPU to operate at thebase frequency, which may be desirable in certain scenarios to prioritize powerefficiency or manage temperature.

To manipulate theboost attribute, users can write a value of0 to disable theboost or1 to enable it, for the respective CPU using the sysfs path/sys/devices/system/cpu/cpuX/cpufreq/boost, whereX represents the CPU number.

Other performance and frequency values can be read back from/sys/devices/system/cpu/cpuX/acpi_cppc/, seeCPPC.

amd-pstate vsacpi-cpufreq

On the majority of AMD platforms supported byacpi-cpufreq, the ACPI tablesprovided by the platform firmware are used for CPU performance scaling, butonly provide 3 P-states on AMD processors.However, on modern AMD APU and CPU series, hardware provides the CollaborativeProcessor Performance Control according to the ACPI protocol and customizes thisfor AMD platforms. That is, fine-grained and continuous frequency rangesinstead of the legacy hardware P-states.amd-pstate is the kernelmodule which supports the new AMD P-States mechanism on most of the future AMDplatforms. The AMD P-States mechanism is the more performance and energyefficiency frequency management method on AMD processors.

amd-pstate Driver Operation Modes

amd_pstate CPPC has 3 operation modes: autonomous (active) mode,non-autonomous (passive) mode and guided autonomous (guided) mode.Active/passive/guided mode can be chosen by different kernel parameters.

  • In autonomous mode, platform ignores the desired performance level requestand takes into account only the values set to the minimum, maximum and energyperformance preference registers.

  • In non-autonomous mode, platform gets desired performance levelfrom OS directly through Desired Performance Register.

  • In guided-autonomous mode, platform sets operating performance levelautonomously according to the current workload and within the limits set byOS through min and max performance registers.

Active Mode

amd_pstate=active

This is the low-level firmware control mode which is implemented byamd_pstate_eppdriver withamd_pstate=active passed to the kernel in the command line.In this mode,amd_pstate_epp driver provides a hint to the hardware if softwarewants to bias toward performance (0x0) or energy efficiency (0xff) to the CPPC firmware.then CPPC power algorithm will calculate the runtime workload and adjust the realtimecores frequency according to the power supply and thermal, core voltage and some otherhardware conditions.

Passive Mode

amd_pstate=passive

It will be enabled if theamd_pstate=passive is passed to the kernel in the command line.In this mode,amd_pstate driver software specifies a desired QoS target in the CPPCperformance scale as a relative number. This can be expressed as percentage of nominalperformance (infrastructure max). Below the nominal sustained performance level,desired performance expresses the average performance level of the processor subjectto the Performance Reduction Tolerance register. Above the nominal performance level,processor must provide at least nominal performance requested and go higher if currentoperating conditions allow.

Guided Mode

amd_pstate=guided

Ifamd_pstate=guided is passed to kernel command line option then this modeis activated. In this mode, driver requests minimum and maximum performancelevel and the platform autonomously selects a performance level in this rangeand appropriate to the current workload.

amd-pstate Preferred Core

The core frequency is subjected to the process variation in semiconductors.Not all cores are able to reach the maximum frequency respecting theinfrastructure limits. Consequently, AMD has redefined the concept ofmaximum frequency of a part. This means that a fraction of cores can reachmaximum frequency. To find the best process scheduling policy for a givenscenario, OS needs to know the core ordering informed by the platform throughhighest performance capability register of the CPPC interface.

amd-pstate preferred core enables the scheduler to prefer scheduling oncores that can achieve a higher frequency with lower voltage. The preferredcore rankings can dynamically change based on the workload, platform conditions,thermals and ageing.

The priority metric will be initialized by theamd-pstate driver. Theamd-pstatedriver will also determine whether or notamd-pstate preferred core issupported by the platform.

amd-pstate driver will provide an initial core ordering when the system boots.The platform uses the CPPC interfaces to communicate the core ranking to theoperating system and scheduler to make sure that OS is choosing the coreswith highest performance firstly for scheduling the process. Whenamd-pstatedriver receives a message with the highest performance change, it willupdate the core ranking and set the cpu’s priority.

amd-pstate Preferred Core Switch

Kernel Parameters

amd-pstate peferred core`` has two states: enable and disable.Enable/disable states can be chosen by different kernel parameters.Default enableamd-pstate preferred core.

amd_prefcore=disable

For systems that supportamd-pstate preferred core, the core rankings willalways be advertised by the platform. But OS can choose to ignore that via thekernel parameteramd_prefcore=disable.

User Space Interface insysfs - General

Global Attributes

amd-pstate exposes several global attributes (files) insysfs tocontrol its functionality at the system level. They are located in the/sys/devices/system/cpu/amd_pstate/ directory and affect all CPUs.

status

Operation mode of the driver: “active”, “passive”, “guided” or “disable”.

“active”

The driver is functional and in theactivemode

“passive”

The driver is functional and in thepassivemode

“guided”

The driver is functional and in theguidedmode

“disable”

The driver is unregistered and not functional now.

This attribute can be written to in order to change the driver’soperation mode or to unregister it. The string written to it must beone of the possible values of it and, if successful, writing one ofthese values to the sysfs file will cause the driver to switch overto the operation mode represented by that string - or to beunregistered in the “disable” case.

prefcore

Preferred core state of the driver: “enabled” or “disabled”.

“enabled”

Enable theamd-pstate preferred core.

“disabled”

Disable theamd-pstate preferred core

This attribute is read-only to check the state of preferred core setby the kernel parameter.

cpupower tool support foramd-pstate

amd-pstate is supported by thecpupower tool, which can be used to dumpfrequency information. Development is in progress to support more and moreoperations for the newamd-pstate module with this tool.

root@hr-test1:/home/ray# cpupower frequency-infoanalyzing CPU 0:  driver: amd-pstate  CPUs which run at the same hardware frequency: 0  CPUs which need to have their frequency coordinated by software: 0  maximum transition latency: 131 us  hardware limits: 400 MHz - 4.68 GHz  available cpufreq governors: ondemand conservative powersave userspace performance schedutil  current policy: frequency should be within 400 MHz and 4.68 GHz.                  The governor "schedutil" may decide which speed to use                  within this range.  current CPU frequency: Unable to call hardware  current CPU frequency: 4.02 GHz (asserted by call to kernel)  boost state support:    Supported: yes    Active: yes    AMD PSTATE Highest Performance: 166. Maximum Frequency: 4.68 GHz.    AMD PSTATE Nominal Performance: 117. Nominal Frequency: 3.30 GHz.    AMD PSTATE Lowest Non-linear Performance: 39. Lowest Non-linear Frequency: 1.10 GHz.    AMD PSTATE Lowest Performance: 15. Lowest Frequency: 400 MHz.

Diagnostics and Tuning

Trace Events

There are two static trace events that can be used foramd-pstatediagnostics. One of them is thecpu_frequency trace event generally usedbyCPUFreq, and the other one is theamd_pstate_perf trace eventspecific toamd-pstate. The following sequence of shell commands canbe used to enable them and see their output (if the kernel isconfigured to support event tracing).

root@hr-test1:/home/ray# cd /sys/kernel/tracing/root@hr-test1:/sys/kernel/tracing# echo 1 > events/amd_cpu/enableroot@hr-test1:/sys/kernel/tracing# cat trace# tracer: nop## entries-in-buffer/entries-written: 47827/42233061   #P:2##                                _-----=> irqs-off#                               / _----=> need-resched#                              | / _---=> hardirq/softirq#                              || / _--=> preempt-depth#                              ||| /     delay#           TASK-PID     CPU#  ||||   TIMESTAMP  FUNCTION#              | |         |   ||||      |         |         <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=true         <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=true            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=true           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=true         <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=true         <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=true         <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=true

Thecpu_frequency trace event will be triggered either by theschedutil scalinggovernor (for the policies it is attached to), or by theCPUFreq core (for thepolicies with other scaling governors).

Tracer Tool

amd_pstate_tracer.py can record and parseamd-pstate trace log, thengenerate performance plots. This utility can be used to debug and tune theperformance ofamd-pstate driver. The tracer tool needs to import intelpstate tracer.

Tracer tool located inlinux/tools/power/x86/amd_pstate_tracer. It can beused in two ways. If trace file is available, then directly parse the filewith command

./amd_pstate_trace.py [-c cpus] -t <trace_file> -n <test_name>

Or generate trace file with root privilege, then parse and plot with command

sudo ./amd_pstate_trace.py [-c cpus] -n <test_name> -i <interval> [-m kbytes]

The test result can be found inresults/test_name. Following is the exampleabout part of the output.

common_cpu  common_secs  common_usecs  min_perf  des_perf  max_perf  freq    mperf   apef    tsc       load   duration_ms  sample_num  elapsed_time  common_commCPU_005     712          116384        39        49        166       0.7565  9645075 2214891 38431470  25.1   11.646       469         2.496         kworker/5:0-40CPU_006     712          116408        39        49        166       0.6769  8950227 1839034 37192089  24.06  11.272       470         2.496         kworker/6:0-1264

Unit Tests for amd-pstate

amd-pstate-ut is a test module for testing theamd-pstate driver.

  • It can help all users to verify their processor support (SBIOS/Firmware or Hardware).

  • Kernel can have a basic function test to avoid the kernel regression during the update.

  • We can introduce more functional or performance tests to align the result together, it will benefit power and performance scale optimization.

  1. Test case descriptions

    1). Basic tests

    Test prerequisite and basic functions for theamd-pstate driver.

    Index

    Functions

    Description

    1

    amd_pstate_ut_acpi_cpc_valid

    Check whether the _CPC object is present in SBIOS.

    The detail refer toProcessor Support.

    2

    amd_pstate_ut_check_enabled

    Check whether AMD P-State is enabled.

    AMD P-States and ACPI hardware P-States always can be supported in one processor.But AMD P-States has the higher priority and if it is enabled withMSR_AMD_CPPC_ENABLE orcppc_set_enable, it will respond to therequest from AMD P-States.

    3

    amd_pstate_ut_check_perf

    Check if the each performance values are reasonable.
    highest_perf >= nominal_perf > lowest_nonlinear_perf > lowest_perf > 0.

    4

    amd_pstate_ut_check_freq

    Check if the each frequency values and max freq when set support boost modeare reasonable.
    max_freq >= nominal_freq > lowest_nonlinear_freq > min_freq > 0
    If boost is not active but supported, this maximum frequency will be larger thanthe one incpuinfo.

    2). Tbench test

    Test and monitor the cpu changes when running tbench benchmark under the specified governor.These changes include desire performance, frequency, load, performance, energy etc.The specified governor is ondemand or schedutil.Tbench can also be tested on theacpi-cpufreq kernel driver for comparison.

    3). Gitsource test

    Test and monitor the cpu changes when running gitsource benchmark under the specified governor.These changes include desire performance, frequency, load, time, energy etc.The specified governor is ondemand or schedutil.Gitsource can also be tested on theacpi-cpufreq kernel driver for comparison.

  2. How to execute the tests

    We use test module in the kselftest frameworks to implement it.We createamd-pstate-ut module and tie it into kselftest.(fordetails refer to Linux Kernel Selftests[4]).

    1). Build

    • open theCONFIG_X86_AMD_PSTATE configuration option.

    • set theCONFIG_X86_AMD_PSTATE_UT configuration option to M.

    • make project

    • make selftest

      $ cd linux$ make -C tools/testing/selftests

    • make perf

      $ cd tools/perf/$ make

    2). Installation & Steps

    $ make -C tools/testing/selftests install INSTALL_PATH=~/kselftest$ cp tools/perf/perf /usr/bin/perf$ sudo ./kselftest/run_kselftest.sh -c amd-pstate

    3). Specified test case

    $ cd ~/kselftest/amd-pstate$ sudo ./run.sh -t basic$ sudo ./run.sh -t tbench$ sudo ./run.sh -t tbench -m acpi-cpufreq$ sudo ./run.sh -t gitsource$ sudo ./run.sh -t gitsource -m acpi-cpufreq$ ./run.sh --help./run.sh: illegal option -- -Usage: ./run.sh [OPTION...]        [-h <help>]        [-o <output-file-for-dump>]        [-c <all: All testing,             basic: Basic testing,             tbench: Tbench testing,             gitsource: Gitsource testing.>]        [-t <tbench time limit>]        [-p <tbench process number>]        [-l <loop times for tbench>]        [-i <amd tracer interval>]        [-m <comparative test: acpi-cpufreq>]

    4). Results

    • basic

    When you finish test, you will get the following log info

    $ dmesg | grep "amd_pstate_ut" | tee log.txt[12977.570663] amd_pstate_ut: 1    amd_pstate_ut_acpi_cpc_valid  success![12977.570673] amd_pstate_ut: 2    amd_pstate_ut_check_enabled   success![12977.571207] amd_pstate_ut: 3    amd_pstate_ut_check_perf      success![12977.571212] amd_pstate_ut: 4    amd_pstate_ut_check_freq      success!

    • tbench

    When you finish test, you will get selftest.tbench.csv and png images.The selftest.tbench.csv file contains the raw data and the drop of the comparative test.The png images shows the performance, energy and performan per watt of each test.Open selftest.tbench.csv :

    Governor

    Round

    Des-perf

    Freq

    Load

    Performance

    Energy

    Performance Per Watt

    Unit

    GHz

    MB/s

    J

    MB/J

    amd-pstate-ondemand

    1

    2504.05

    1563.67

    158.5378

    amd-pstate-ondemand

    2

    2243.64

    1430.32

    155.2941

    amd-pstate-ondemand

    3

    2183.88

    1401.32

    154.2860

    amd-pstate-ondemand

    Average

    2310.52

    1465.1

    156.1268

    amd-pstate-schedutil

    1

    165.329

    1.62257

    99.798

    2136.54

    1395.26

    151.5971

    amd-pstate-schedutil

    2

    166

    1.49761

    99.9993

    2100.56

    1380.5

    150.6377

    amd-pstate-schedutil

    3

    166

    1.47806

    99.9993

    2084.12

    1375.76

    149.9737

    amd-pstate-schedutil

    Average

    165.776

    1.53275

    99.9322

    2107.07

    1383.84

    150.7399

    acpi-cpufreq-ondemand

    1

    2529.9

    1564.4

    160.0997

    acpi-cpufreq-ondemand

    2

    2249.76

    1432.97

    155.4297

    acpi-cpufreq-ondemand

    3

    2181.46

    1406.88

    153.5060

    acpi-cpufreq-ondemand

    Average

    2320.37

    1468.08

    156.4741

    acpi-cpufreq-schedutil

    1

    2137.64

    1385.24

    152.7723

    acpi-cpufreq-schedutil

    2

    2107.05

    1372.23

    152.0138

    acpi-cpufreq-schedutil

    3

    2085.86

    1365.35

    151.2433

    acpi-cpufreq-schedutil

    Average

    2110.18

    1374.27

    152.0136

    acpi-cpufreq-ondemand VS acpi-cpufreq-schedutil

    Comprison(%)

    -9.0584

    -6.3899

    -2.8506

    amd-pstate-ondemand VS amd-pstate-schedutil

    Comprison(%)

    8.8053

    -5.5463

    -3.4503

    acpi-cpufreq-ondemand VS amd-pstate-ondemand

    Comprison(%)

    -0.4245

    -0.2029

    -0.2219

    acpi-cpufreq-schedutil VS amd-pstate-schedutil

    Comprison(%)

    -0.1473

    0.6963

    -0.8378

    • gitsource

    When you finish test, you will get selftest.gitsource.csv and png images.The selftest.gitsource.csv file contains the raw data and the drop of the comparative test.The png images shows the performance, energy and performan per watt of each test.Open selftest.gitsource.csv :

    Governor

    Round

    Des-perf

    Freq

    Load

    Time

    Energy

    Performance Per Watt

    Unit

    GHz

    s

    J

    1/J

    amd-pstate-ondemand

    1

    50.119

    2.10509

    23.3076

    475.69

    865.78

    0.001155027

    amd-pstate-ondemand

    2

    94.8006

    1.98771

    56.6533

    467.1

    839.67

    0.001190944

    amd-pstate-ondemand

    3

    76.6091

    2.53251

    43.7791

    467.69

    855.85

    0.001168429

    amd-pstate-ondemand

    Average

    73.8429

    2.20844

    41.2467

    470.16

    853.767

    0.001171279

    amd-pstate-schedutil

    1

    165.919

    1.62319

    98.3868

    464.17

    866.8

    0.001153668

    amd-pstate-schedutil

    2

    165.97

    1.31309

    99.5712

    480.15

    880.4

    0.001135847

    amd-pstate-schedutil

    3

    165.973

    1.28448

    99.9252

    481.79

    867.02

    0.001153375

    amd-pstate-schedutil

    Average

    165.954

    1.40692

    99.2944

    475.37

    871.407

    0.001147569

    acpi-cpufreq-ondemand

    1

    2379.62

    742.96

    0.001345967

    acpi-cpufreq-ondemand

    2

    441.74

    817.49

    0.001223256

    acpi-cpufreq-ondemand

    3

    455.48

    820.01

    0.001219497

    acpi-cpufreq-ondemand

    Average

    425.613

    793.487

    0.001260260

    acpi-cpufreq-schedutil

    1

    459.69

    838.54

    0.001192548

    acpi-cpufreq-schedutil

    2

    466.55

    830.89

    0.001203528

    acpi-cpufreq-schedutil

    3

    470.38

    837.32

    0.001194286

    acpi-cpufreq-schedutil

    Average

    465.54

    835.583

    0.001196769

    acpi-cpufreq-ondemand VS acpi-cpufreq-schedutil

    Comprison(%)

    9.3810

    5.3051

    -5.0379

    amd-pstate-ondemand VS amd-pstate-schedutil

    Comprison(%)

    124.7392

    -36.2934

    140.7329

    1.1081

    2.0661

    -2.0242

    acpi-cpufreq-ondemand VS amd-pstate-ondemand

    Comprison(%)

    10.4665

    7.5968

    -7.0605

    acpi-cpufreq-schedutil VS amd-pstate-schedutil

    Comprison(%)

    2.1115

    4.2873

    -4.1110

Reference

[1]

AMD64 Architecture Programmer’s Manual Volume 2: System Programming,https://www.amd.com/system/files/TechDocs/24593.pdf

[2]

Advanced Configuration and Power Interface Specification,https://uefi.org/sites/default/files/resources/ACPI_Spec_6_4_Jan22.pdf

[3]

Processor Programming Reference (PPR) for AMD Family 19h Model 51h, Revision A1 Processorshttps://www.amd.com/system/files/TechDocs/56569-A1-PUB.zip

[4]

Linux Kernel Selftests,https://www.kernel.org/doc/html/latest/dev-tools/kselftest.html