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 13 Introduction 14 =================== 15 16 ``amd-pstate`` is the AMD CPU performance scaling driver that introduces a 17 new CPU frequency control mechanism on modern AMD APU and CPU series in 18 Linux kernel. The new mechanism is based on Collaborative Processor 19 Performance Control (CPPC) which provides finer grain frequency management 20 than legacy ACPI hardware P-States. Current AMD CPU/APU platforms are using 21 the ACPI P-states driver to manage CPU frequency and clocks with switching 22 only in 3 P-states. CPPC replaces the ACPI P-states controls and allows a 23 flexible, low-latency interface for the Linux kernel to directly 24 communicate 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 28 CPPC hardware functionality that internally follows the hardware 29 specification (for details refer to AMD64 Architecture Programmer's Manual 30 Volume 2: System Programming [1]_). Currently, ``amd-pstate`` supports basic 31 frequency control function according to kernel governors on some of the 32 Zen2 and Zen3 processors, and we will implement more AMD specific functions 33 in future after we verify them on the hardware and SBIOS. 34 35 36 AMD CPPC Overview 37 ======================= 38 39 Collaborative Processor Performance Control (CPPC) interface enumerates a 40 continuous, abstract, and unit-less performance value in a scale that is 41 not tied to a specific performance state / frequency. This is an ACPI 42 standard [2]_ which software can specify application performance goals and 43 hints as a relative target to the infrastructure limits. AMD processors 44 provide the low latency register model (MSR) instead of an AML code 45 interpreter for performance adjustments. ``amd-pstate`` will initialize a 46 ``struct cpufreq_driver`` instance, ``amd_pstate_driver``, with the callbacks 47 to 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 88 AMD CPPC Performance Capability 89 -------------------------------- 90 91 Highest Performance (RO) 92 ......................... 93 94 This is the absolute maximum performance an individual processor may reach, 95 assuming ideal conditions. This performance level may not be sustainable 96 for long durations and may only be achievable if other platform components 97 are in a specific state; for example, it may require other processors to be in 98 an idle state. This would be equivalent to the highest frequencies 99 supported by the processor. 100 101 Nominal (Guaranteed) Performance (RO) 102 ...................................... 103 104 This is the maximum sustained performance level of the processor, assuming 105 ideal operating conditions. In the absence of an external constraint (power, 106 thermal, etc.), this is the performance level the processor is expected to 107 be able to maintain continuously. All cores/processors are expected to be 108 able to sustain their nominal performance state simultaneously. 109 110 Lowest non-linear Performance (RO) 111 ................................... 112 113 This is the lowest performance level at which nonlinear power savings are 114 achieved, for example, due to the combined effects of voltage and frequency 115 scaling. Above this threshold, lower performance levels should be generally 116 more energy efficient than higher performance levels. This register 117 effectively conveys the most efficient performance level to ``amd-pstate``. 118 119 Lowest Performance (RO) 120 ........................ 121 122 This is the absolute lowest performance level of the processor. Selecting a 123 performance level lower than the lowest nonlinear performance level may 124 cause an efficiency penalty but should reduce the instantaneous power 125 consumption of the processor. 126 127 AMD CPPC Performance Control 128 ------------------------------ 129 130 ``amd-pstate`` passes performance goals through these registers. The 131 register drives the behavior of the desired performance target. 132 133 Minimum requested performance (RW) 134 ................................... 135 136 ``amd-pstate`` specifies the minimum allowed performance level. 137 138 Maximum requested performance (RW) 139 ................................... 140 141 ``amd-pstate`` specifies a limit the maximum performance that is expected 142 to be supplied by the hardware. 143 144 Desired performance target (RW) 145 ................................... 146 147 ``amd-pstate`` specifies a desired target in the CPPC performance scale as 148 a relative number. This can be expressed as percentage of nominal 149 performance (infrastructure max). Below the nominal sustained performance 150 level, desired performance expresses the average performance level of the 151 processor subject to hardware. Above the nominal performance level, 152 the processor must provide at least nominal performance requested and go higher 153 if current operating conditions allow. 154 155 Energy Performance Preference (EPP) (RW) 156 ......................................... 157 158 This attribute provides a hint to the hardware if software wants to bias 159 toward performance (0x0) or energy efficiency (0xff). 160 161 162 Key Governors Support 163 ======================= 164 165 ``amd-pstate`` can be used with all the (generic) scaling governors listed 166 by the ``scaling_available_governors`` policy attribute in ``sysfs``. Then, 167 it is responsible for the configuration of policy objects corresponding to 168 CPUs and provides the ``CPUFreq`` core (and the scaling governors attached 169 to the policy objects) with accurate information on the maximum and minimum 170 operating 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 174 frequency control. It is to fine tune the processor configuration on 175 ``amd-pstate`` to the ``schedutil`` with CPU CFS scheduler. ``amd-pstate`` 176 registers the adjust_perf callback to implement performance update behavior 177 similar to CPPC. It is initialized by ``sugov_start`` and then populates the 178 CPU's update_util_data pointer to assign ``sugov_update_single_perf`` as the 179 utilization update callback function in the CPU scheduler. The CPU scheduler 180 will call ``cpufreq_update_util`` and assigns the target performance according 181 to the ``struct sugov_cpu`` that the utilization update belongs to. 182 Then, ``amd-pstate`` updates the desired performance according to the CPU 183 scheduler assigned. 184 185 .. _processor_support: 186 187 Processor Support 188 ======================= 189 190 The ``amd-pstate`` initialization will fail if the ``_CPC`` entry in the ACPI 191 SBIOS does not exist in the detected processor. It uses ``acpi_cpc_valid`` 192 to check the existence of ``_CPC``. All Zen based processors support the legacy 193 ACPI hardware P-States function, so when ``amd-pstate`` fails initialization, 194 the kernel will fall back to initialize the ``acpi-cpufreq`` driver. 195 196 There 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 199 indicate the different types. (For details, refer to the Processor Programming 200 Reference (PPR) for AMD Family 19h Model 51h, Revision A1 Processors [3]_.) 201 ``amd-pstate`` is to register different ``static_call`` instances for different 202 hardware implementations. 203 204 Currently, some of the Zen2 and Zen3 processors support ``amd-pstate``. In the 205 future, it will be supported on more and more AMD processors. 206 207 Full MSR Support 208 ----------------- 209 210 Some new Zen3 processors such as Cezanne provide the MSR registers directly 211 while the :c:macro:`X86_FEATURE_CPPC` CPU feature flag is set. 212 ``amd-pstate`` can handle the MSR register to implement the fast switch 213 function in ``CPUFreq`` that can reduce the latency of frequency control in 214 interrupt context. The functions with a ``pstate_xxx`` prefix represent the 215 operations on MSR registers. 216 217 Shared Memory Support 218 ---------------------- 219 220 If the :c:macro:`X86_FEATURE_CPPC` CPU feature flag is not set, the 221 processor supports the shared memory solution. In this case, ``amd-pstate`` 222 uses the ``cppc_acpi`` helper methods to implement the callback functions 223 that are defined on ``static_call``. The functions with the ``cppc_xxx`` prefix 224 represent the operations of ACPI CPPC helpers for the shared memory solution. 225 226 227 AMD P-States and ACPI hardware P-States always can be supported in one 228 processor. But AMD P-States has the higher priority and if it is enabled 229 with :c:macro:`MSR_AMD_CPPC_ENABLE` or ``cppc_set_enable``, it will respond 230 to the request from AMD P-States. 231 232 233 User Space Interface in ``sysfs`` - Per-policy control 234 ====================================================== 235 236 ``amd-pstate`` exposes several global attributes (files) in ``sysfs`` to 237 control 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`` 247 248 Maximum CPPC performance and CPU frequency that the driver is allowed to 249 set, in percent of the maximum supported CPPC performance level (the highest 250 performance supported in `AMD CPPC Performance Capability <perf_cap_>`_). 251 In some ASICs, the highest CPPC performance is not the one in the ``_CPC`` 252 table, so we need to expose it to sysfs. If boost is not active, but 253 still supported, this maximum frequency will be larger than the one in 254 ``cpuinfo``. On systems that support preferred core, the driver will have 255 different values for some cores than others and this will reflect the values 256 advertised by the platform at bootup. 257 This attribute is read-only. 258 259 ``amd_pstate_lowest_nonlinear_freq`` 260 261 The lowest non-linear CPPC CPU frequency that the driver is allowed to set, 262 in percent of the maximum supported CPPC performance level. (Please see the 263 lowest non-linear performance in `AMD CPPC Performance Capability 264 <perf_cap_>`_.) 265 This attribute is read-only. 266 267 ``amd_pstate_hw_prefcore`` 268 269 Whether the platform supports the preferred core feature and it has been 270 enabled. This attribute is read-only. 271 272 ``amd_pstate_prefcore_ranking`` 273 274 The performance ranking of the core. This number doesn't have any unit, but 275 larger numbers are preferred at the time of reading. This can change at 276 runtime based on platform conditions. This attribute is read-only. 277 278 ``energy_performance_available_preferences`` 279 280 A list of all the supported EPP preferences that could be used for 281 ``energy_performance_preference`` on this system. 282 These profiles represent different hints that are provided 283 to the low-level firmware about the user's desired energy vs efficiency 284 tradeoff. ``default`` represents the epp value is set by platform 285 firmware. This attribute is read-only. 286 287 ``energy_performance_preference`` 288 289 The current energy performance preference can be read from this attribute. 290 and user can change current preference according to energy or performance needs 291 Please get all support profiles list from 292 ``energy_performance_available_preferences`` attribute, all the profiles are 293 integer values defined between 0 to 255 when EPP feature is enabled by platform 294 firmware, if EPP feature is disabled, driver will ignore the written value 295 This attribute is read-write. 296 297 ``boost`` 298 The `boost` sysfs attribute provides control over the CPU core 299 performance boost, allowing users to manage the maximum frequency limitation 300 of the CPU. This attribute can be used to enable or disable the boost feature 301 on individual CPUs. 302 303 When the boost feature is enabled, the CPU can dynamically increase its frequency 304 beyond the base frequency, providing enhanced performance for demanding workloads. 305 On the other hand, disabling the boost feature restricts the CPU to operate at the 306 base frequency, which may be desirable in certain scenarios to prioritize power 307 efficiency or manage temperature. 308 309 To manipulate the `boost` attribute, users can write a value of `0` to disable the 310 boost or `1` to enable it, for the respective CPU using the sysfs path 311 `/sys/devices/system/cpu/cpuX/cpufreq/boost`, where `X` represents the CPU number. 312 313 Other performance and frequency values can be read back from 314 ``/sys/devices/system/cpu/cpuX/acpi_cppc/``, see :ref:`cppc_sysfs`. 315 316 317 ``amd-pstate`` vs ``acpi-cpufreq`` 318 ====================================== 319 320 On the majority of AMD platforms supported by ``acpi-cpufreq``, the ACPI tables 321 provided by the platform firmware are used for CPU performance scaling, but 322 only provide 3 P-states on AMD processors. 323 However, on modern AMD APU and CPU series, hardware provides the Collaborative 324 Processor Performance Control according to the ACPI protocol and customizes this 325 for AMD platforms. That is, fine-grained and continuous frequency ranges 326 instead of the legacy hardware P-states. ``amd-pstate`` is the kernel 327 module which supports the new AMD P-States mechanism on most of the future AMD 328 platforms. The AMD P-States mechanism is the more performance and energy 329 efficiency frequency management method on AMD processors. 330 331 332 ``amd-pstate`` Driver Operation Modes 333 ====================================== 334 335 ``amd_pstate`` CPPC has 3 operation modes: autonomous (active) mode, 336 non-autonomous (passive) mode and guided autonomous (guided) mode. 337 Active/passive/guided mode can be chosen by different kernel parameters. 338 339 - In autonomous mode, platform ignores the desired performance level request 340 and takes into account only the values set to the minimum, maximum and energy 341 performance preference registers. 342 - In non-autonomous mode, platform gets desired performance level 343 from OS directly through Desired Performance Register. 344 - In guided-autonomous mode, platform sets operating performance level 345 autonomously according to the current workload and within the limits set by 346 OS through min and max performance registers. 347 348 Active Mode 349 ------------ 350 351 ``amd_pstate=active`` 352 353 This is the low-level firmware control mode which is implemented by ``amd_pstate_epp`` 354 driver with ``amd_pstate=active`` passed to the kernel in the command line. 355 In this mode, ``amd_pstate_epp`` driver provides a hint to the hardware if software 356 wants to bias toward performance (0x0) or energy efficiency (0xff) to the CPPC firmware. 357 then CPPC power algorithm will calculate the runtime workload and adjust the realtime 358 cores frequency according to the power supply and thermal, core voltage and some other 359 hardware conditions. 360 361 Passive Mode 362 ------------ 363 364 ``amd_pstate=passive`` 365 366 It will be enabled if the ``amd_pstate=passive`` is passed to the kernel in the command line. 367 In this mode, ``amd_pstate`` driver software specifies a desired QoS target in the CPPC 368 performance scale as a relative number. This can be expressed as percentage of nominal 369 performance (infrastructure max). Below the nominal sustained performance level, 370 desired performance expresses the average performance level of the processor subject 371 to the Performance Reduction Tolerance register. Above the nominal performance level, 372 processor must provide at least nominal performance requested and go higher if current 373 operating conditions allow. 374 375 Guided Mode 376 ----------- 377 378 ``amd_pstate=guided`` 379 380 If ``amd_pstate=guided`` is passed to kernel command line option then this mode 381 is activated. In this mode, driver requests minimum and maximum performance 382 level and the platform autonomously selects a performance level in this range 383 and appropriate to the current workload. 384 385 ``amd-pstate`` Preferred Core 386 ================================= 387 388 The core frequency is subjected to the process variation in semiconductors. 389 Not all cores are able to reach the maximum frequency respecting the 390 infrastructure limits. Consequently, AMD has redefined the concept of 391 maximum frequency of a part. This means that a fraction of cores can reach 392 maximum frequency. To find the best process scheduling policy for a given 393 scenario, OS needs to know the core ordering informed by the platform through 394 highest performance capability register of the CPPC interface. 395 396 ``amd-pstate`` preferred core enables the scheduler to prefer scheduling on 397 cores that can achieve a higher frequency with lower voltage. The preferred 398 core rankings can dynamically change based on the workload, platform conditions, 399 thermals and ageing. 400 401 The priority metric will be initialized by the ``amd-pstate`` driver. The ``amd-pstate`` 402 driver will also determine whether or not ``amd-pstate`` preferred core is 403 supported by the platform. 404 405 ``amd-pstate`` driver will provide an initial core ordering when the system boots. 406 The platform uses the CPPC interfaces to communicate the core ranking to the 407 operating system and scheduler to make sure that OS is choosing the cores 408 with highest performance firstly for scheduling the process. When ``amd-pstate`` 409 driver receives a message with the highest performance change, it will 410 update the core ranking and set the cpu's priority. 411 412 ``amd-pstate`` Preferred Core Switch 413 ===================================== 414 Kernel Parameters 415 ----------------- 416 417 ``amd-pstate`` peferred core`` has two states: enable and disable. 418 Enable/disable states can be chosen by different kernel parameters. 419 Default enable ``amd-pstate`` preferred core. 420 421 ``amd_prefcore=disable`` 422 423 For systems that support ``amd-pstate`` preferred core, the core rankings will 424 always be advertised by the platform. But OS can choose to ignore that via the 425 kernel parameter ``amd_prefcore=disable``. 426 427 User Space Interface in ``sysfs`` - General 428 =========================================== 429 430 Global Attributes 431 ----------------- 432 433 ``amd-pstate`` exposes several global attributes (files) in ``sysfs`` to 434 control its functionality at the system level. They are located in the 435 ``/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's 453 operation mode or to unregister it. The string written to it must be 454 one of the possible values of it and, if successful, writing one of 455 these values to the sysfs file will cause the driver to switch over 456 to the operation mode represented by that string - or to be 457 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 core 467 468 469 This attribute is read-only to check the state of preferred core set 470 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 dump 476 frequency information. Development is in progress to support more and more 477 operations for the new ``amd-pstate`` module with this tool. :: 478 479 root@hr-test1:/home/ray# cpupower frequency-info 480 analyzing CPU 0: 481 driver: amd-pstate 482 CPUs which run at the same hardware frequency: 0 483 CPUs which need to have their frequency coordinated by software: 0 484 maximum transition latency: 131 us 485 hardware limits: 400 MHz - 4.68 GHz 486 available cpufreq governors: ondemand conservative powersave userspace performance schedutil 487 current policy: frequency should be within 400 MHz and 4.68 GHz. 488 The governor "schedutil" may decide which speed to use 489 within this range. 490 current CPU frequency: Unable to call hardware 491 current CPU frequency: 4.02 GHz (asserted by call to kernel) 492 boost state support: 493 Supported: yes 494 Active: yes 495 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. 499 500 501 Diagnostics and Tuning 502 ======================= 503 504 Trace Events 505 -------------- 506 507 There are two static trace events that can be used for ``amd-pstate`` 508 diagnostics. One of them is the ``cpu_frequency`` trace event generally used 509 by ``CPUFreq``, and the other one is the ``amd_pstate_perf`` trace event 510 specific to ``amd-pstate``. The following sequence of shell commands can 511 be used to enable them and see their output (if the kernel is 512 configured 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/enable 516 root@hr-test1:/sys/kernel/tracing# cat trace 517 # tracer: nop 518 # 519 # entries-in-buffer/entries-written: 47827/42233061 #P:2 520 # 521 # _-----=> irqs-off 522 # / _----=> need-resched 523 # | / _---=> hardirq/softirq 524 # || / _--=> preempt-depth 525 # ||| / delay 526 # TASK-PID CPU# |||| TIMESTAMP FUNCTION 527 # | | | |||| | | 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=true 529 <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 530 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 531 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 532 <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 533 <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 534 <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 535 536 The ``cpu_frequency`` trace event will be triggered either by the ``schedutil`` scaling 537 governor (for the policies it is attached to), or by the ``CPUFreq`` core (for the 538 policies with other scaling governors). 539 540 541 Tracer Tool 542 ------------- 543 544 ``amd_pstate_tracer.py`` can record and parse ``amd-pstate`` trace log, then 545 generate performance plots. This utility can be used to debug and tune the 546 performance of ``amd-pstate`` driver. The tracer tool needs to import intel 547 pstate tracer. 548 549 Tracer tool located in ``linux/tools/power/x86/amd_pstate_tracer``. It can be 550 used in two ways. If trace file is available, then directly parse the file 551 with command :: 552 553 ./amd_pstate_trace.py [-c cpus] -t <trace_file> -n <test_name> 554 555 Or 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] 558 559 The test result can be found in ``results/test_name``. Following is the example 560 about 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_comm 563 CPU_005 712 116384 39 49 166 0.7565 9645075 2214891 38431470 25.1 11.646 469 2.496 kworker/5:0-40 564 CPU_006 712 116408 39 49 166 0.6769 8950227 1839034 37192089 24.06 11.272 470 2.496 kworker/6:0-1264 565 566 Unit Tests for amd-pstate 567 ------------------------- 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. 576 577 1. Test case descriptions 578 579 1). Basic tests 580 581 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 test 608 609 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 test 615 616 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 tests 622 623 We use test module in the kselftest frameworks to implement it. 624 We create ``amd-pstate-ut`` module and tie it into kselftest.(for 625 details refer to Linux Kernel Selftests [4]_). 626 627 1). Build 628 629 + 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 project 632 + make selftest :: 633 634 $ cd linux 635 $ make -C tools/testing/selftests 636 637 + make perf :: 638 639 $ cd tools/perf/ 640 $ make 641 642 643 2). Installation & Steps :: 644 645 $ make -C tools/testing/selftests install INSTALL_PATH=~/kselftest 646 $ cp tools/perf/perf /usr/bin/perf 647 $ sudo ./kselftest/run_kselftest.sh -c amd-pstate 648 649 3). Specified test case :: 650 651 $ cd ~/kselftest/amd-pstate 652 $ sudo ./run.sh -t basic 653 $ sudo ./run.sh -t tbench 654 $ sudo ./run.sh -t tbench -m acpi-cpufreq 655 $ sudo ./run.sh -t gitsource 656 $ sudo ./run.sh -t gitsource -m acpi-cpufreq 657 $ ./run.sh --help 658 ./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). Results 674 675 + basic 676 677 When you finish test, you will get the following log info :: 678 679 $ dmesg | grep "amd_pstate_ut" | tee log.txt 680 [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 + tbench 686 687 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 + gitsource 739 740 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 +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ 790 791 Reference 792 =========== 793 794 .. [1] AMD64 Architecture Programmer's Manual Volume 2: System Programming, 795 https://www.amd.com/system/files/TechDocs/24593.pdf 796 797 .. [2] Advanced Configuration and Power Interface Specification, 798 https://uefi.org/sites/default/files/resources/ACPI_Spec_6_4_Jan22.pdf 799 800 .. [3] Processor Programming Reference (PPR) for AMD Family 19h Model 51h, Revision A1 Processors 801 https://www.amd.com/system/files/TechDocs/56569-A1-PUB.zip 802 803 .. [4] Linux Kernel Selftests, 804 https://www.kernel.org/doc/html/latest/dev-tools/kselftest.html
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