1.. SPDX-License-Identifier: GPL-2.0 2.. include:: <isonum.txt> 3 4=============================================== 5``amd-pstate`` CPU Performance Scaling Driver 6=============================================== 7 8:Copyright: |copy| 2021 Advanced Micro Devices, Inc. 9 10:Author: Huang Rui <ray.huang@amd.com> 11 12 13Introduction 14=================== 15 16``amd-pstate`` is the AMD CPU performance scaling driver that introduces a 17new CPU frequency control mechanism on modern AMD APU and CPU series in 18Linux kernel. The new mechanism is based on Collaborative Processor 19Performance Control (CPPC) which provides finer grain frequency management 20than legacy ACPI hardware P-States. Current AMD CPU/APU platforms are using 21the ACPI P-states driver to manage CPU frequency and clocks with switching 22only in 3 P-states. CPPC replaces the ACPI P-states controls and allows a 23flexible, low-latency interface for the Linux kernel to directly 24communicate 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 by 28CPPC hardware functionality that internally follows the hardware 29specification (for details refer to AMD64 Architecture Programmer's Manual 30Volume 2: System Programming [1]_). Currently, ``amd-pstate`` supports basic 31frequency control function according to kernel governors on some of the 32Zen2 and Zen3 processors, and we will implement more AMD specific functions 33in future after we verify them on the hardware and SBIOS. 34 35 36AMD CPPC Overview 37======================= 38 39Collaborative Processor Performance Control (CPPC) interface enumerates a 40continuous, abstract, and unit-less performance value in a scale that is 41not tied to a specific performance state / frequency. This is an ACPI 42standard [2]_ which software can specify application performance goals and 43hints as a relative target to the infrastructure limits. AMD processors 44provide the low latency register model (MSR) instead of an AML code 45interpreter for performance adjustments. ``amd-pstate`` will initialize a 46``struct cpufreq_driver`` instance, ``amd_pstate_driver``, with the callbacks 47to 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 Scale 84 85 86.. _perf_cap: 87 88AMD CPPC Performance Capability 89-------------------------------- 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 sustainable 96for long durations and may only be achievable if other platform components 97are in a specific state; for example, it may require other processors to be in 98an idle state. This would be equivalent to the highest frequencies 99supported by the processor. 100 101Nominal (Guaranteed) Performance (RO) 102...................................... 103 104This is the maximum sustained performance level of the processor, assuming 105ideal operating conditions. In the absence of an external constraint (power, 106thermal, etc.), this is the performance level the processor is expected to 107be able to maintain continuously. All cores/processors are expected to be 108able 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 are 114achieved, for example, due to the combined effects of voltage and frequency 115scaling. Above this threshold, lower performance levels should be generally 116more energy efficient than higher performance levels. This register 117effectively 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 a 123performance level lower than the lowest nonlinear performance level may 124cause an efficiency penalty but should reduce the instantaneous power 125consumption of the processor. 126 127AMD CPPC Performance Control 128------------------------------ 129 130``amd-pstate`` passes performance goals through these registers. The 131register 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 expected 142to be supplied by the hardware. 143 144Desired performance target (RW) 145................................... 146 147``amd-pstate`` specifies a desired target in the CPPC performance scale as 148a relative number. This can be expressed as percentage of nominal 149performance (infrastructure max). Below the nominal sustained performance 150level, desired performance expresses the average performance level of the 151processor subject to hardware. Above the nominal performance level, 152the processor must provide at least nominal performance requested and go higher 153if current operating conditions allow. 154 155Energy Performance Preference (EPP) (RW) 156......................................... 157 158This attribute provides a hint to the hardware if software wants to bias 159toward performance (0x0) or energy efficiency (0xff). 160 161 162Key Governors Support 163======================= 164 165``amd-pstate`` can be used with all the (generic) scaling governors listed 166by the ``scaling_available_governors`` policy attribute in ``sysfs``. Then, 167it is responsible for the configuration of policy objects corresponding to 168CPUs and provides the ``CPUFreq`` core (and the scaling governors attached 169to the policy objects) with accurate information on the maximum and minimum 170operating frequencies supported by the hardware. Users can check the 171``scaling_cur_freq`` information comes from the ``CPUFreq`` core. 172 173``amd-pstate`` mainly supports ``schedutil`` and ``ondemand`` for dynamic 174frequency control. It is to fine tune the processor configuration on 175``amd-pstate`` to the ``schedutil`` with CPU CFS scheduler. ``amd-pstate`` 176registers the adjust_perf callback to implement performance update behavior 177similar to CPPC. It is initialized by ``sugov_start`` and then populates the 178CPU's update_util_data pointer to assign ``sugov_update_single_perf`` as the 179utilization update callback function in the CPU scheduler. The CPU scheduler 180will call ``cpufreq_update_util`` and assigns the target performance according 181to the ``struct sugov_cpu`` that the utilization update belongs to. 182Then, ``amd-pstate`` updates the desired performance according to the CPU 183scheduler assigned. 184 185.. _processor_support: 186 187Processor Support 188======================= 189 190The ``amd-pstate`` initialization will fail if the ``_CPC`` entry in the ACPI 191SBIOS does not exist in the detected processor. It uses ``acpi_cpc_valid`` 192to check the existence of ``_CPC``. All Zen based processors support the legacy 193ACPI 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 is 197`Full MSR Support <perf_cap_>`_ and another is `Shared Memory Support 198<perf_cap_>`_. It can use the :c:macro:`X86_FEATURE_CPPC` feature flag to 199indicate the different types. (For details, refer to the Processor Programming 200Reference (PPR) for AMD Family 19h Model 51h, Revision A1 Processors [3]_.) 201``amd-pstate`` is to register different ``static_call`` instances for different 202hardware implementations. 203 204Currently, some of the Zen2 and Zen3 processors support ``amd-pstate``. In the 205future, it will be supported on more and more AMD processors. 206 207Full MSR Support 208----------------- 209 210Some new Zen3 processors such as Cezanne provide the MSR registers directly 211while the :c:macro:`X86_FEATURE_CPPC` CPU feature flag is set. 212``amd-pstate`` can handle the MSR register to implement the fast switch 213function in ``CPUFreq`` that can reduce the latency of frequency control in 214interrupt context. The functions with a ``pstate_xxx`` prefix represent the 215operations on MSR registers. 216 217Shared Memory Support 218---------------------- 219 220If the :c:macro:`X86_FEATURE_CPPC` CPU feature flag is not set, the 221processor supports the shared memory solution. In this case, ``amd-pstate`` 222uses the ``cppc_acpi`` helper methods to implement the callback functions 223that are defined on ``static_call``. The functions with the ``cppc_xxx`` prefix 224represent 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 one 228processor. But AMD P-States has the higher priority and if it is enabled 229with :c:macro:`MSR_AMD_CPPC_ENABLE` or ``cppc_set_enable``, it will respond 230to the request from AMD P-States. 231 232 233User Space Interface in ``sysfs`` - Per-policy control 234====================================================== 235 236``amd-pstate`` exposes several global attributes (files) in ``sysfs`` to 237control its functionality at the system level. They are located in the 238``/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_perf 242 /sys/devices/system/cpu/cpufreq/policy0/amd_pstate_lowest_nonlinear_freq 243 /sys/devices/system/cpu/cpufreq/policy0/amd_pstate_max_freq 244 245 246``amd_pstate_highest_perf / amd_pstate_max_freq`` 247 248Maximum CPPC performance and CPU frequency that the driver is allowed to 249set, in percent of the maximum supported CPPC performance level (the highest 250performance 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, but 253still supported, this maximum frequency will be larger than the one in 254``cpuinfo``. 255This attribute is read-only. 256 257``amd_pstate_lowest_nonlinear_freq`` 258 259The lowest non-linear CPPC CPU frequency that the driver is allowed to set, 260in percent of the maximum supported CPPC performance level. (Please see the 261lowest non-linear performance in `AMD CPPC Performance Capability 262<perf_cap_>`_.) 263This attribute is read-only. 264 265``amd_pstate_hw_prefcore`` 266 267Whether the platform supports the preferred core feature and it has been 268enabled. This attribute is read-only. 269 270``amd_pstate_prefcore_ranking`` 271 272The performance ranking of the core. This number doesn't have any unit, but 273larger numbers are preferred at the time of reading. This can change at 274runtime based on platform conditions. This attribute is read-only. 275 276``energy_performance_available_preferences`` 277 278A list of all the supported EPP preferences that could be used for 279``energy_performance_preference`` on this system. 280These profiles represent different hints that are provided 281to the low-level firmware about the user's desired energy vs efficiency 282tradeoff. ``default`` represents the epp value is set by platform 283firmware. This attribute is read-only. 284 285``energy_performance_preference`` 286 287The current energy performance preference can be read from this attribute. 288and user can change current preference according to energy or performance needs 289Please get all support profiles list from 290``energy_performance_available_preferences`` attribute, all the profiles are 291integer values defined between 0 to 255 when EPP feature is enabled by platform 292firmware, if EPP feature is disabled, driver will ignore the written value 293This attribute is read-write. 294 295``boost`` 296The `boost` sysfs attribute provides control over the CPU core 297performance boost, allowing users to manage the maximum frequency limitation 298of the CPU. This attribute can be used to enable or disable the boost feature 299on individual CPUs. 300 301When the boost feature is enabled, the CPU can dynamically increase its frequency 302beyond the base frequency, providing enhanced performance for demanding workloads. 303On the other hand, disabling the boost feature restricts the CPU to operate at the 304base frequency, which may be desirable in certain scenarios to prioritize power 305efficiency or manage temperature. 306 307To manipulate the `boost` attribute, users can write a value of `0` to disable the 308boost or `1` to enable it, for the respective CPU using the sysfs path 309`/sys/devices/system/cpu/cpuX/cpufreq/boost`, where `X` represents the CPU number. 310 311Other performance and frequency values can be read back from 312``/sys/devices/system/cpu/cpuX/acpi_cppc/``, see :ref:`cppc_sysfs`. 313 314 315``amd-pstate`` vs ``acpi-cpufreq`` 316====================================== 317 318On the majority of AMD platforms supported by ``acpi-cpufreq``, the ACPI tables 319provided by the platform firmware are used for CPU performance scaling, but 320only provide 3 P-states on AMD processors. 321However, on modern AMD APU and CPU series, hardware provides the Collaborative 322Processor Performance Control according to the ACPI protocol and customizes this 323for AMD platforms. That is, fine-grained and continuous frequency ranges 324instead of the legacy hardware P-states. ``amd-pstate`` is the kernel 325module which supports the new AMD P-States mechanism on most of the future AMD 326platforms. The AMD P-States mechanism is the more performance and energy 327efficiency frequency management method on AMD processors. 328 329 330``amd-pstate`` Driver Operation Modes 331====================================== 332 333``amd_pstate`` CPPC has 3 operation modes: autonomous (active) mode, 334non-autonomous (passive) mode and guided autonomous (guided) mode. 335Active/passive/guided mode can be chosen by different kernel parameters. 336 337- In autonomous mode, platform ignores the desired performance level request 338 and takes into account only the values set to the minimum, maximum and energy 339 performance preference registers. 340- In non-autonomous mode, platform gets desired performance level 341 from OS directly through Desired Performance Register. 342- In guided-autonomous mode, platform sets operating performance level 343 autonomously according to the current workload and within the limits set by 344 OS through min and max performance registers. 345 346Active Mode 347------------ 348 349``amd_pstate=active`` 350 351This is the low-level firmware control mode which is implemented by ``amd_pstate_epp`` 352driver with ``amd_pstate=active`` passed to the kernel in the command line. 353In this mode, ``amd_pstate_epp`` driver provides a hint to the hardware if software 354wants to bias toward performance (0x0) or energy efficiency (0xff) to the CPPC firmware. 355then CPPC power algorithm will calculate the runtime workload and adjust the realtime 356cores frequency according to the power supply and thermal, core voltage and some other 357hardware conditions. 358 359Passive Mode 360------------ 361 362``amd_pstate=passive`` 363 364It will be enabled if the ``amd_pstate=passive`` is passed to the kernel in the command line. 365In this mode, ``amd_pstate`` driver software specifies a desired QoS target in the CPPC 366performance scale as a relative number. This can be expressed as percentage of nominal 367performance (infrastructure max). Below the nominal sustained performance level, 368desired performance expresses the average performance level of the processor subject 369to the Performance Reduction Tolerance register. Above the nominal performance level, 370processor must provide at least nominal performance requested and go higher if current 371operating conditions allow. 372 373Guided Mode 374----------- 375 376``amd_pstate=guided`` 377 378If ``amd_pstate=guided`` is passed to kernel command line option then this mode 379is activated. In this mode, driver requests minimum and maximum performance 380level and the platform autonomously selects a performance level in this range 381and appropriate to the current workload. 382 383``amd-pstate`` Preferred Core 384================================= 385 386The core frequency is subjected to the process variation in semiconductors. 387Not all cores are able to reach the maximum frequency respecting the 388infrastructure limits. Consequently, AMD has redefined the concept of 389maximum frequency of a part. This means that a fraction of cores can reach 390maximum frequency. To find the best process scheduling policy for a given 391scenario, OS needs to know the core ordering informed by the platform through 392highest performance capability register of the CPPC interface. 393 394``amd-pstate`` preferred core enables the scheduler to prefer scheduling on 395cores that can achieve a higher frequency with lower voltage. The preferred 396core rankings can dynamically change based on the workload, platform conditions, 397thermals and ageing. 398 399The priority metric will be initialized by the ``amd-pstate`` driver. The ``amd-pstate`` 400driver will also determine whether or not ``amd-pstate`` preferred core is 401supported by the platform. 402 403``amd-pstate`` driver will provide an initial core ordering when the system boots. 404The platform uses the CPPC interfaces to communicate the core ranking to the 405operating system and scheduler to make sure that OS is choosing the cores 406with highest performance firstly for scheduling the process. When ``amd-pstate`` 407driver receives a message with the highest performance change, it will 408update the core ranking and set the cpu's priority. 409 410``amd-pstate`` Preferred Core Switch 411===================================== 412Kernel Parameters 413----------------- 414 415``amd-pstate`` peferred core`` has two states: enable and disable. 416Enable/disable states can be chosen by different kernel parameters. 417Default enable ``amd-pstate`` preferred core. 418 419``amd_prefcore=disable`` 420 421For systems that support ``amd-pstate`` preferred core, the core rankings will 422always be advertised by the platform. But OS can choose to ignore that via the 423kernel parameter ``amd_prefcore=disable``. 424 425User Space Interface in ``sysfs`` - General 426=========================================== 427 428Global Attributes 429----------------- 430 431``amd-pstate`` exposes several global attributes (files) in ``sysfs`` to 432control its functionality at the system level. They are located in the 433``/sys/devices/system/cpu/amd_pstate/`` directory and affect all CPUs. 434 435``status`` 436 Operation mode of the driver: "active", "passive", "guided" or "disable". 437 438 "active" 439 The driver is functional and in the ``active mode`` 440 441 "passive" 442 The driver is functional and in the ``passive mode`` 443 444 "guided" 445 The driver is functional and in the ``guided mode`` 446 447 "disable" 448 The driver is unregistered and not functional now. 449 450 This attribute can be written to in order to change the driver's 451 operation mode or to unregister it. The string written to it must be 452 one of the possible values of it and, if successful, writing one of 453 these values to the sysfs file will cause the driver to switch over 454 to the operation mode represented by that string - or to be 455 unregistered in the "disable" case. 456 457``prefcore`` 458 Preferred core state of the driver: "enabled" or "disabled". 459 460 "enabled" 461 Enable the ``amd-pstate`` preferred core. 462 463 "disabled" 464 Disable the ``amd-pstate`` preferred core 465 466 467 This attribute is read-only to check the state of preferred core set 468 by the kernel parameter. 469 470``cpupower`` tool support for ``amd-pstate`` 471=============================================== 472 473``amd-pstate`` is supported by the ``cpupower`` tool, which can be used to dump 474frequency information. Development is in progress to support more and more 475operations for the new ``amd-pstate`` module with this tool. :: 476 477 root@hr-test1:/home/ray# cpupower frequency-info 478 analyzing CPU 0: 479 driver: amd-pstate 480 CPUs which run at the same hardware frequency: 0 481 CPUs which need to have their frequency coordinated by software: 0 482 maximum transition latency: 131 us 483 hardware limits: 400 MHz - 4.68 GHz 484 available cpufreq governors: ondemand conservative powersave userspace performance schedutil 485 current policy: frequency should be within 400 MHz and 4.68 GHz. 486 The governor "schedutil" may decide which speed to use 487 within this range. 488 current CPU frequency: Unable to call hardware 489 current CPU frequency: 4.02 GHz (asserted by call to kernel) 490 boost state support: 491 Supported: yes 492 Active: yes 493 AMD PSTATE Highest Performance: 166. Maximum Frequency: 4.68 GHz. 494 AMD PSTATE Nominal Performance: 117. Nominal Frequency: 3.30 GHz. 495 AMD PSTATE Lowest Non-linear Performance: 39. Lowest Non-linear Frequency: 1.10 GHz. 496 AMD PSTATE Lowest Performance: 15. Lowest Frequency: 400 MHz. 497 498 499Diagnostics and Tuning 500======================= 501 502Trace Events 503-------------- 504 505There are two static trace events that can be used for ``amd-pstate`` 506diagnostics. One of them is the ``cpu_frequency`` trace event generally used 507by ``CPUFreq``, and the other one is the ``amd_pstate_perf`` trace event 508specific to ``amd-pstate``. The following sequence of shell commands can 509be used to enable them and see their output (if the kernel is 510configured to support event tracing). :: 511 512 root@hr-test1:/home/ray# cd /sys/kernel/tracing/ 513 root@hr-test1:/sys/kernel/tracing# echo 1 > events/amd_cpu/enable 514 root@hr-test1:/sys/kernel/tracing# cat trace 515 # tracer: nop 516 # 517 # entries-in-buffer/entries-written: 47827/42233061 #P:2 518 # 519 # _-----=> irqs-off 520 # / _----=> need-resched 521 # | / _---=> hardirq/softirq 522 # || / _--=> preempt-depth 523 # ||| / delay 524 # TASK-PID CPU# |||| TIMESTAMP FUNCTION 525 # | | | |||| | | 526 <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 527 <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 528 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 529 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 530 <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 531 <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 532 <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 533 534The ``cpu_frequency`` trace event will be triggered either by the ``schedutil`` scaling 535governor (for the policies it is attached to), or by the ``CPUFreq`` core (for the 536policies with other scaling governors). 537 538 539Tracer Tool 540------------- 541 542``amd_pstate_tracer.py`` can record and parse ``amd-pstate`` trace log, then 543generate performance plots. This utility can be used to debug and tune the 544performance of ``amd-pstate`` driver. The tracer tool needs to import intel 545pstate tracer. 546 547Tracer tool located in ``linux/tools/power/x86/amd_pstate_tracer``. It can be 548used in two ways. If trace file is available, then directly parse the file 549with command :: 550 551 ./amd_pstate_trace.py [-c cpus] -t <trace_file> -n <test_name> 552 553Or generate trace file with root privilege, then parse and plot with command :: 554 555 sudo ./amd_pstate_trace.py [-c cpus] -n <test_name> -i <interval> [-m kbytes] 556 557The test result can be found in ``results/test_name``. Following is the example 558about part of the output. :: 559 560 common_cpu common_secs common_usecs min_perf des_perf max_perf freq mperf apef tsc load duration_ms sample_num elapsed_time common_comm 561 CPU_005 712 116384 39 49 166 0.7565 9645075 2214891 38431470 25.1 11.646 469 2.496 kworker/5:0-40 562 CPU_006 712 116408 39 49 166 0.6769 8950227 1839034 37192089 24.06 11.272 470 2.496 kworker/6:0-1264 563 564Unit Tests for amd-pstate 565------------------------- 566 567``amd-pstate-ut`` is a test module for testing the ``amd-pstate`` driver. 568 569 * It can help all users to verify their processor support (SBIOS/Firmware or Hardware). 570 571 * Kernel can have a basic function test to avoid the kernel regression during the update. 572 573 * We can introduce more functional or performance tests to align the result together, it will benefit power and performance scale optimization. 574 5751. Test case descriptions 576 577 1). Basic tests 578 579 Test prerequisite and basic functions for the ``amd-pstate`` driver. 580 581 +---------+--------------------------------+------------------------------------------------------------------------------------+ 582 | Index | Functions | Description | 583 +=========+================================+====================================================================================+ 584 | 1 | amd_pstate_ut_acpi_cpc_valid || Check whether the _CPC object is present in SBIOS. | 585 | | || | 586 | | || The detail refer to `Processor Support <processor_support_>`_. | 587 +---------+--------------------------------+------------------------------------------------------------------------------------+ 588 | 2 | amd_pstate_ut_check_enabled || Check whether AMD P-State is enabled. | 589 | | || | 590 | | || AMD P-States and ACPI hardware P-States always can be supported in one processor. | 591 | | | But AMD P-States has the higher priority and if it is enabled with | 592 | | | :c:macro:`MSR_AMD_CPPC_ENABLE` or ``cppc_set_enable``, it will respond to the | 593 | | | request from AMD P-States. | 594 +---------+--------------------------------+------------------------------------------------------------------------------------+ 595 | 3 | amd_pstate_ut_check_perf || Check if the each performance values are reasonable. | 596 | | || highest_perf >= nominal_perf > lowest_nonlinear_perf > lowest_perf > 0. | 597 +---------+--------------------------------+------------------------------------------------------------------------------------+ 598 | 4 | amd_pstate_ut_check_freq || Check if the each frequency values and max freq when set support boost mode | 599 | | | are reasonable. | 600 | | || max_freq >= nominal_freq > lowest_nonlinear_freq > min_freq > 0 | 601 | | || If boost is not active but supported, this maximum frequency will be larger than | 602 | | | the one in ``cpuinfo``. | 603 +---------+--------------------------------+------------------------------------------------------------------------------------+ 604 605 2). Tbench test 606 607 Test and monitor the cpu changes when running tbench benchmark under the specified governor. 608 These changes include desire performance, frequency, load, performance, energy etc. 609 The specified governor is ondemand or schedutil. 610 Tbench can also be tested on the ``acpi-cpufreq`` kernel driver for comparison. 611 612 3). Gitsource test 613 614 Test and monitor the cpu changes when running gitsource benchmark under the specified governor. 615 These changes include desire performance, frequency, load, time, energy etc. 616 The specified governor is ondemand or schedutil. 617 Gitsource can also be tested on the ``acpi-cpufreq`` kernel driver for comparison. 618 619#. How to execute the tests 620 621 We use test module in the kselftest frameworks to implement it. 622 We create ``amd-pstate-ut`` module and tie it into kselftest.(for 623 details refer to Linux Kernel Selftests [4]_). 624 625 1). Build 626 627 + open the :c:macro:`CONFIG_X86_AMD_PSTATE` configuration option. 628 + set the :c:macro:`CONFIG_X86_AMD_PSTATE_UT` configuration option to M. 629 + make project 630 + make selftest :: 631 632 $ cd linux 633 $ make -C tools/testing/selftests 634 635 + make perf :: 636 637 $ cd tools/perf/ 638 $ make 639 640 641 2). Installation & Steps :: 642 643 $ make -C tools/testing/selftests install INSTALL_PATH=~/kselftest 644 $ cp tools/perf/perf /usr/bin/perf 645 $ sudo ./kselftest/run_kselftest.sh -c amd-pstate 646 647 3). Specified test case :: 648 649 $ cd ~/kselftest/amd-pstate 650 $ sudo ./run.sh -t basic 651 $ sudo ./run.sh -t tbench 652 $ sudo ./run.sh -t tbench -m acpi-cpufreq 653 $ sudo ./run.sh -t gitsource 654 $ sudo ./run.sh -t gitsource -m acpi-cpufreq 655 $ ./run.sh --help 656 ./run.sh: illegal option -- - 657 Usage: ./run.sh [OPTION...] 658 [-h <help>] 659 [-o <output-file-for-dump>] 660 [-c <all: All testing, 661 basic: Basic testing, 662 tbench: Tbench testing, 663 gitsource: Gitsource testing.>] 664 [-t <tbench time limit>] 665 [-p <tbench process number>] 666 [-l <loop times for tbench>] 667 [-i <amd tracer interval>] 668 [-m <comparative test: acpi-cpufreq>] 669 670 671 4). Results 672 673 + basic 674 675 When you finish test, you will get the following log info :: 676 677 $ dmesg | grep "amd_pstate_ut" | tee log.txt 678 [12977.570663] amd_pstate_ut: 1 amd_pstate_ut_acpi_cpc_valid success! 679 [12977.570673] amd_pstate_ut: 2 amd_pstate_ut_check_enabled success! 680 [12977.571207] amd_pstate_ut: 3 amd_pstate_ut_check_perf success! 681 [12977.571212] amd_pstate_ut: 4 amd_pstate_ut_check_freq success! 682 683 + tbench 684 685 When you finish test, you will get selftest.tbench.csv and png images. 686 The selftest.tbench.csv file contains the raw data and the drop of the comparative test. 687 The png images shows the performance, energy and performan per watt of each test. 688 Open selftest.tbench.csv : 689 690 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ 691 + Governor | Round | Des-perf | Freq | Load | Performance | Energy | Performance Per Watt | 692 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ 693 + Unit | | | GHz | | MB/s | J | MB/J | 694 +=================================================+==============+==========+=========+==========+=============+=========+======================+ 695 + amd-pstate-ondemand | 1 | | | | 2504.05 | 1563.67 | 158.5378 | 696 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ 697 + amd-pstate-ondemand | 2 | | | | 2243.64 | 1430.32 | 155.2941 | 698 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ 699 + amd-pstate-ondemand | 3 | | | | 2183.88 | 1401.32 | 154.2860 | 700 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ 701 + amd-pstate-ondemand | Average | | | | 2310.52 | 1465.1 | 156.1268 | 702 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ 703 + amd-pstate-schedutil | 1 | 165.329 | 1.62257 | 99.798 | 2136.54 | 1395.26 | 151.5971 | 704 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ 705 + amd-pstate-schedutil | 2 | 166 | 1.49761 | 99.9993 | 2100.56 | 1380.5 | 150.6377 | 706 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ 707 + amd-pstate-schedutil | 3 | 166 | 1.47806 | 99.9993 | 2084.12 | 1375.76 | 149.9737 | 708 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ 709 + amd-pstate-schedutil | Average | 165.776 | 1.53275 | 99.9322 | 2107.07 | 1383.84 | 150.7399 | 710 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ 711 + acpi-cpufreq-ondemand | 1 | | | | 2529.9 | 1564.4 | 160.0997 | 712 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ 713 + acpi-cpufreq-ondemand | 2 | | | | 2249.76 | 1432.97 | 155.4297 | 714 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ 715 + acpi-cpufreq-ondemand | 3 | | | | 2181.46 | 1406.88 | 153.5060 | 716 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ 717 + acpi-cpufreq-ondemand | Average | | | | 2320.37 | 1468.08 | 156.4741 | 718 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ 719 + acpi-cpufreq-schedutil | 1 | | | | 2137.64 | 1385.24 | 152.7723 | 720 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ 721 + acpi-cpufreq-schedutil | 2 | | | | 2107.05 | 1372.23 | 152.0138 | 722 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ 723 + acpi-cpufreq-schedutil | 3 | | | | 2085.86 | 1365.35 | 151.2433 | 724 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ 725 + acpi-cpufreq-schedutil | Average | | | | 2110.18 | 1374.27 | 152.0136 | 726 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ 727 + acpi-cpufreq-ondemand VS acpi-cpufreq-schedutil | Comprison(%) | | | | -9.0584 | -6.3899 | -2.8506 | 728 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ 729 + amd-pstate-ondemand VS amd-pstate-schedutil | Comprison(%) | | | | 8.8053 | -5.5463 | -3.4503 | 730 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ 731 + acpi-cpufreq-ondemand VS amd-pstate-ondemand | Comprison(%) | | | | -0.4245 | -0.2029 | -0.2219 | 732 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ 733 + acpi-cpufreq-schedutil VS amd-pstate-schedutil | Comprison(%) | | | | -0.1473 | 0.6963 | -0.8378 | 734 +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ 735 736 + gitsource 737 738 When you finish test, you will get selftest.gitsource.csv and png images. 739 The selftest.gitsource.csv file contains the raw data and the drop of the comparative test. 740 The png images shows the performance, energy and performan per watt of each test. 741 Open selftest.gitsource.csv : 742 743 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ 744 + Governor | Round | Des-perf | Freq | Load | Time | Energy | Performance Per Watt | 745 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ 746 + Unit | | | GHz | | s | J | 1/J | 747 +=================================================+==============+==========+==========+==========+=============+=========+======================+ 748 + amd-pstate-ondemand | 1 | 50.119 | 2.10509 | 23.3076 | 475.69 | 865.78 | 0.001155027 | 749 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ 750 + amd-pstate-ondemand | 2 | 94.8006 | 1.98771 | 56.6533 | 467.1 | 839.67 | 0.001190944 | 751 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ 752 + amd-pstate-ondemand | 3 | 76.6091 | 2.53251 | 43.7791 | 467.69 | 855.85 | 0.001168429 | 753 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ 754 + amd-pstate-ondemand | Average | 73.8429 | 2.20844 | 41.2467 | 470.16 | 853.767 | 0.001171279 | 755 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ 756 + amd-pstate-schedutil | 1 | 165.919 | 1.62319 | 98.3868 | 464.17 | 866.8 | 0.001153668 | 757 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ 758 + amd-pstate-schedutil | 2 | 165.97 | 1.31309 | 99.5712 | 480.15 | 880.4 | 0.001135847 | 759 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ 760 + amd-pstate-schedutil | 3 | 165.973 | 1.28448 | 99.9252 | 481.79 | 867.02 | 0.001153375 | 761 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ 762 + amd-pstate-schedutil | Average | 165.954 | 1.40692 | 99.2944 | 475.37 | 871.407 | 0.001147569 | 763 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ 764 + acpi-cpufreq-ondemand | 1 | | | | 2379.62 | 742.96 | 0.001345967 | 765 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ 766 + acpi-cpufreq-ondemand | 2 | | | | 441.74 | 817.49 | 0.001223256 | 767 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ 768 + acpi-cpufreq-ondemand | 3 | | | | 455.48 | 820.01 | 0.001219497 | 769 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ 770 + acpi-cpufreq-ondemand | Average | | | | 425.613 | 793.487 | 0.001260260 | 771 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ 772 + acpi-cpufreq-schedutil | 1 | | | | 459.69 | 838.54 | 0.001192548 | 773 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ 774 + acpi-cpufreq-schedutil | 2 | | | | 466.55 | 830.89 | 0.001203528 | 775 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ 776 + acpi-cpufreq-schedutil | 3 | | | | 470.38 | 837.32 | 0.001194286 | 777 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ 778 + acpi-cpufreq-schedutil | Average | | | | 465.54 | 835.583 | 0.001196769 | 779 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ 780 + acpi-cpufreq-ondemand VS acpi-cpufreq-schedutil | Comprison(%) | | | | 9.3810 | 5.3051 | -5.0379 | 781 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ 782 + amd-pstate-ondemand VS amd-pstate-schedutil | Comprison(%) | 124.7392 | -36.2934 | 140.7329 | 1.1081 | 2.0661 | -2.0242 | 783 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ 784 + acpi-cpufreq-ondemand VS amd-pstate-ondemand | Comprison(%) | | | | 10.4665 | 7.5968 | -7.0605 | 785 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ 786 + acpi-cpufreq-schedutil VS amd-pstate-schedutil | Comprison(%) | | | | 2.1115 | 4.2873 | -4.1110 | 787 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ 788 789Reference 790=========== 791 792.. [1] AMD64 Architecture Programmer's Manual Volume 2: System Programming, 793 https://www.amd.com/system/files/TechDocs/24593.pdf 794 795.. [2] Advanced Configuration and Power Interface Specification, 796 https://uefi.org/sites/default/files/resources/ACPI_Spec_6_4_Jan22.pdf 797 798.. [3] Processor Programming Reference (PPR) for AMD Family 19h Model 51h, Revision A1 Processors 799 https://www.amd.com/system/files/TechDocs/56569-A1-PUB.zip 800 801.. [4] Linux Kernel Selftests, 802 https://www.kernel.org/doc/html/latest/dev-tools/kselftest.html 803