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``
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
265Other performance and frequency values can be read back from
266``/sys/devices/system/cpu/cpuX/acpi_cppc/``, see :ref:`cppc_sysfs`.
267
268
269``amd-pstate`` vs ``acpi-cpufreq``
270======================================
271
272On the majority of AMD platforms supported by ``acpi-cpufreq``, the ACPI tables
273provided by the platform firmware are used for CPU performance scaling, but
274only provide 3 P-states on AMD processors.
275However, on modern AMD APU and CPU series, hardware provides the Collaborative
276Processor Performance Control according to the ACPI protocol and customizes this
277for AMD platforms. That is, fine-grained and continuous frequency ranges
278instead of the legacy hardware P-states. ``amd-pstate`` is the kernel
279module which supports the new AMD P-States mechanism on most of the future AMD
280platforms. The AMD P-States mechanism is the more performance and energy
281efficiency frequency management method on AMD processors.
282
283Kernel Module Options for ``amd-pstate``
284=========================================
285
286Passive Mode
287------------
288
289``amd_pstate=passive``
290
291It will be enabled if the ``amd_pstate=passive`` is passed to the kernel in the command line.
292In this mode, ``amd_pstate`` driver software specifies a desired QoS target in the CPPC
293performance scale as a relative number. This can be expressed as percentage of nominal
294performance (infrastructure max). Below the nominal sustained performance level,
295desired performance expresses the average performance level of the processor subject
296to the Performance Reduction Tolerance register. Above the nominal performance level,
297processor must provide at least nominal performance requested and go higher if current
298operating conditions allow.
299
300
301``cpupower`` tool support for ``amd-pstate``
302===============================================
303
304``amd-pstate`` is supported by the ``cpupower`` tool, which can be used to dump
305frequency information. Development is in progress to support more and more
306operations for the new ``amd-pstate`` module with this tool. ::
307
308 root@hr-test1:/home/ray# cpupower frequency-info
309 analyzing CPU 0:
310   driver: amd-pstate
311   CPUs which run at the same hardware frequency: 0
312   CPUs which need to have their frequency coordinated by software: 0
313   maximum transition latency: 131 us
314   hardware limits: 400 MHz - 4.68 GHz
315   available cpufreq governors: ondemand conservative powersave userspace performance schedutil
316   current policy: frequency should be within 400 MHz and 4.68 GHz.
317                   The governor "schedutil" may decide which speed to use
318                   within this range.
319   current CPU frequency: Unable to call hardware
320   current CPU frequency: 4.02 GHz (asserted by call to kernel)
321   boost state support:
322     Supported: yes
323     Active: yes
324     AMD PSTATE Highest Performance: 166. Maximum Frequency: 4.68 GHz.
325     AMD PSTATE Nominal Performance: 117. Nominal Frequency: 3.30 GHz.
326     AMD PSTATE Lowest Non-linear Performance: 39. Lowest Non-linear Frequency: 1.10 GHz.
327     AMD PSTATE Lowest Performance: 15. Lowest Frequency: 400 MHz.
328
329
330Diagnostics and Tuning
331=======================
332
333Trace Events
334--------------
335
336There are two static trace events that can be used for ``amd-pstate``
337diagnostics. One of them is the ``cpu_frequency`` trace event generally used
338by ``CPUFreq``, and the other one is the ``amd_pstate_perf`` trace event
339specific to ``amd-pstate``.  The following sequence of shell commands can
340be used to enable them and see their output (if the kernel is
341configured to support event tracing). ::
342
343 root@hr-test1:/home/ray# cd /sys/kernel/tracing/
344 root@hr-test1:/sys/kernel/tracing# echo 1 > events/amd_cpu/enable
345 root@hr-test1:/sys/kernel/tracing# cat trace
346 # tracer: nop
347 #
348 # entries-in-buffer/entries-written: 47827/42233061   #P:2
349 #
350 #                                _-----=> irqs-off
351 #                               / _----=> need-resched
352 #                              | / _---=> hardirq/softirq
353 #                              || / _--=> preempt-depth
354 #                              ||| /     delay
355 #           TASK-PID     CPU#  ||||   TIMESTAMP  FUNCTION
356 #              | |         |   ||||      |         |
357          <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
358          <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
359             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
360            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
361          <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
362          <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
363          <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
364
365The ``cpu_frequency`` trace event will be triggered either by the ``schedutil`` scaling
366governor (for the policies it is attached to), or by the ``CPUFreq`` core (for the
367policies with other scaling governors).
368
369
370Tracer Tool
371-------------
372
373``amd_pstate_tracer.py`` can record and parse ``amd-pstate`` trace log, then
374generate performance plots. This utility can be used to debug and tune the
375performance of ``amd-pstate`` driver. The tracer tool needs to import intel
376pstate tracer.
377
378Tracer tool located in ``linux/tools/power/x86/amd_pstate_tracer``. It can be
379used in two ways. If trace file is available, then directly parse the file
380with command ::
381
382 ./amd_pstate_trace.py [-c cpus] -t <trace_file> -n <test_name>
383
384Or generate trace file with root privilege, then parse and plot with command ::
385
386 sudo ./amd_pstate_trace.py [-c cpus] -n <test_name> -i <interval> [-m kbytes]
387
388The test result can be found in ``results/test_name``. Following is the example
389about part of the output. ::
390
391 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
392 CPU_005     712          116384        39        49        166       0.7565  9645075 2214891 38431470  25.1   11.646       469         2.496         kworker/5:0-40
393 CPU_006     712          116408        39        49        166       0.6769  8950227 1839034 37192089  24.06  11.272       470         2.496         kworker/6:0-1264
394
395Unit Tests for amd-pstate
396-------------------------
397
398``amd-pstate-ut`` is a test module for testing the ``amd-pstate`` driver.
399
400 * It can help all users to verify their processor support (SBIOS/Firmware or Hardware).
401
402 * Kernel can have a basic function test to avoid the kernel regression during the update.
403
404 * We can introduce more functional or performance tests to align the result together, it will benefit power and performance scale optimization.
405
4061. Test case decriptions
407
408    1). Basic tests
409
410        Test prerequisite and basic functions for the ``amd-pstate`` driver.
411
412        +---------+--------------------------------+------------------------------------------------------------------------------------+
413        | Index   | Functions                      | Description                                                                        |
414        +=========+================================+====================================================================================+
415        | 1       | amd_pstate_ut_acpi_cpc_valid   || Check whether the _CPC object is present in SBIOS.                                |
416        |         |                                ||                                                                                   |
417        |         |                                || The detail refer to `Processor Support <processor_support_>`_.                    |
418        +---------+--------------------------------+------------------------------------------------------------------------------------+
419        | 2       | amd_pstate_ut_check_enabled    || Check whether AMD P-State is enabled.                                             |
420        |         |                                ||                                                                                   |
421        |         |                                || AMD P-States and ACPI hardware P-States always can be supported in one processor. |
422        |         |                                | But AMD P-States has the higher priority and if it is enabled with                 |
423        |         |                                | :c:macro:`MSR_AMD_CPPC_ENABLE` or ``cppc_set_enable``, it will respond to the      |
424        |         |                                | request from AMD P-States.                                                         |
425        +---------+--------------------------------+------------------------------------------------------------------------------------+
426        | 3       | amd_pstate_ut_check_perf       || Check if the each performance values are reasonable.                              |
427        |         |                                || highest_perf >= nominal_perf > lowest_nonlinear_perf > lowest_perf > 0.           |
428        +---------+--------------------------------+------------------------------------------------------------------------------------+
429        | 4       | amd_pstate_ut_check_freq       || Check if the each frequency values and max freq when set support boost mode       |
430        |         |                                | are reasonable.                                                                    |
431        |         |                                || max_freq >= nominal_freq > lowest_nonlinear_freq > min_freq > 0                   |
432        |         |                                || If boost is not active but supported, this maximum frequency will be larger than  |
433        |         |                                | the one in ``cpuinfo``.                                                            |
434        +---------+--------------------------------+------------------------------------------------------------------------------------+
435
436    2). Tbench test
437
438        Test and monitor the cpu changes when running tbench benchmark under the specified governor.
439        These changes include desire performance, frequency, load, performance, energy etc.
440        The specified governor is ondemand or schedutil.
441        Tbench can also be tested on the ``acpi-cpufreq`` kernel driver for comparison.
442
443    3). Gitsource test
444
445        Test and monitor the cpu changes when running gitsource benchmark under the specified governor.
446        These changes include desire performance, frequency, load, time, energy etc.
447        The specified governor is ondemand or schedutil.
448        Gitsource can also be tested on the ``acpi-cpufreq`` kernel driver for comparison.
449
450#. How to execute the tests
451
452   We use test module in the kselftest frameworks to implement it.
453   We create ``amd-pstate-ut`` module and tie it into kselftest.(for
454   details refer to Linux Kernel Selftests [4]_).
455
456    1). Build
457
458        + open the :c:macro:`CONFIG_X86_AMD_PSTATE` configuration option.
459        + set the :c:macro:`CONFIG_X86_AMD_PSTATE_UT` configuration option to M.
460        + make project
461        + make selftest ::
462
463            $ cd linux
464            $ make -C tools/testing/selftests
465
466        + make perf ::
467
468            $ cd tools/perf/
469            $ make
470
471
472    2). Installation & Steps ::
473
474        $ make -C tools/testing/selftests install INSTALL_PATH=~/kselftest
475        $ cp tools/perf/perf /usr/bin/perf
476        $ sudo ./kselftest/run_kselftest.sh -c amd-pstate
477
478    3). Specified test case ::
479
480        $ cd ~/kselftest/amd-pstate
481        $ sudo ./run.sh -t basic
482        $ sudo ./run.sh -t tbench
483        $ sudo ./run.sh -t tbench -m acpi-cpufreq
484        $ sudo ./run.sh -t gitsource
485        $ sudo ./run.sh -t gitsource -m acpi-cpufreq
486        $ ./run.sh --help
487        ./run.sh: illegal option -- -
488        Usage: ./run.sh [OPTION...]
489                [-h <help>]
490                [-o <output-file-for-dump>]
491                [-c <all: All testing,
492                     basic: Basic testing,
493                     tbench: Tbench testing,
494                     gitsource: Gitsource testing.>]
495                [-t <tbench time limit>]
496                [-p <tbench process number>]
497                [-l <loop times for tbench>]
498                [-i <amd tracer interval>]
499                [-m <comparative test: acpi-cpufreq>]
500
501
502    4). Results
503
504        + basic
505
506         When you finish test, you will get the following log info ::
507
508          $ dmesg | grep "amd_pstate_ut" | tee log.txt
509          [12977.570663] amd_pstate_ut: 1    amd_pstate_ut_acpi_cpc_valid  success!
510          [12977.570673] amd_pstate_ut: 2    amd_pstate_ut_check_enabled   success!
511          [12977.571207] amd_pstate_ut: 3    amd_pstate_ut_check_perf      success!
512          [12977.571212] amd_pstate_ut: 4    amd_pstate_ut_check_freq      success!
513
514        + tbench
515
516         When you finish test, you will get selftest.tbench.csv and png images.
517         The selftest.tbench.csv file contains the raw data and the drop of the comparative test.
518         The png images shows the performance, energy and performan per watt of each test.
519         Open selftest.tbench.csv :
520
521         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
522         + Governor                                        | Round        | Des-perf | Freq    | Load     | Performance | Energy  | Performance Per Watt |
523         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
524         + Unit                                            |              |          | GHz     |          | MB/s        | J       | MB/J                 |
525         +=================================================+==============+==========+=========+==========+=============+=========+======================+
526         + amd-pstate-ondemand                             | 1            |          |         |          | 2504.05     | 1563.67 | 158.5378             |
527         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
528         + amd-pstate-ondemand                             | 2            |          |         |          | 2243.64     | 1430.32 | 155.2941             |
529         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
530         + amd-pstate-ondemand                             | 3            |          |         |          | 2183.88     | 1401.32 | 154.2860             |
531         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
532         + amd-pstate-ondemand                             | Average      |          |         |          | 2310.52     | 1465.1  | 156.1268             |
533         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
534         + amd-pstate-schedutil                            | 1            | 165.329  | 1.62257 | 99.798   | 2136.54     | 1395.26 | 151.5971             |
535         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
536         + amd-pstate-schedutil                            | 2            | 166      | 1.49761 | 99.9993  | 2100.56     | 1380.5  | 150.6377             |
537         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
538         + amd-pstate-schedutil                            | 3            | 166      | 1.47806 | 99.9993  | 2084.12     | 1375.76 | 149.9737             |
539         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
540         + amd-pstate-schedutil                            | Average      | 165.776  | 1.53275 | 99.9322  | 2107.07     | 1383.84 | 150.7399             |
541         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
542         + acpi-cpufreq-ondemand                           | 1            |          |         |          | 2529.9      | 1564.4  | 160.0997             |
543         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
544         + acpi-cpufreq-ondemand                           | 2            |          |         |          | 2249.76     | 1432.97 | 155.4297             |
545         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
546         + acpi-cpufreq-ondemand                           | 3            |          |         |          | 2181.46     | 1406.88 | 153.5060             |
547         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
548         + acpi-cpufreq-ondemand                           | Average      |          |         |          | 2320.37     | 1468.08 | 156.4741             |
549         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
550         + acpi-cpufreq-schedutil                          | 1            |          |         |          | 2137.64     | 1385.24 | 152.7723             |
551         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
552         + acpi-cpufreq-schedutil                          | 2            |          |         |          | 2107.05     | 1372.23 | 152.0138             |
553         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
554         + acpi-cpufreq-schedutil                          | 3            |          |         |          | 2085.86     | 1365.35 | 151.2433             |
555         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
556         + acpi-cpufreq-schedutil                          | Average      |          |         |          | 2110.18     | 1374.27 | 152.0136             |
557         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
558         + acpi-cpufreq-ondemand VS acpi-cpufreq-schedutil | Comprison(%) |          |         |          | -9.0584     | -6.3899 | -2.8506              |
559         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
560         + amd-pstate-ondemand VS amd-pstate-schedutil     | Comprison(%) |          |         |          | 8.8053      | -5.5463 | -3.4503              |
561         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
562         + acpi-cpufreq-ondemand VS amd-pstate-ondemand    | Comprison(%) |          |         |          | -0.4245     | -0.2029 | -0.2219              |
563         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
564         + acpi-cpufreq-schedutil VS amd-pstate-schedutil  | Comprison(%) |          |         |          | -0.1473     | 0.6963  | -0.8378              |
565         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
566
567        + gitsource
568
569         When you finish test, you will get selftest.gitsource.csv and png images.
570         The selftest.gitsource.csv file contains the raw data and the drop of the comparative test.
571         The png images shows the performance, energy and performan per watt of each test.
572         Open selftest.gitsource.csv :
573
574         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
575         + Governor                                        | Round        | Des-perf | Freq     | Load     | Time        | Energy  | Performance Per Watt |
576         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
577         + Unit                                            |              |          | GHz      |          | s           | J       | 1/J                  |
578         +=================================================+==============+==========+==========+==========+=============+=========+======================+
579         + amd-pstate-ondemand                             | 1            | 50.119   | 2.10509  | 23.3076  | 475.69      | 865.78  | 0.001155027          |
580         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
581         + amd-pstate-ondemand                             | 2            | 94.8006  | 1.98771  | 56.6533  | 467.1       | 839.67  | 0.001190944          |
582         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
583         + amd-pstate-ondemand                             | 3            | 76.6091  | 2.53251  | 43.7791  | 467.69      | 855.85  | 0.001168429          |
584         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
585         + amd-pstate-ondemand                             | Average      | 73.8429  | 2.20844  | 41.2467  | 470.16      | 853.767 | 0.001171279          |
586         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
587         + amd-pstate-schedutil                            | 1            | 165.919  | 1.62319  | 98.3868  | 464.17      | 866.8   | 0.001153668          |
588         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
589         + amd-pstate-schedutil                            | 2            | 165.97   | 1.31309  | 99.5712  | 480.15      | 880.4   | 0.001135847          |
590         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
591         + amd-pstate-schedutil                            | 3            | 165.973  | 1.28448  | 99.9252  | 481.79      | 867.02  | 0.001153375          |
592         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
593         + amd-pstate-schedutil                            | Average      | 165.954  | 1.40692  | 99.2944  | 475.37      | 871.407 | 0.001147569          |
594         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
595         + acpi-cpufreq-ondemand                           | 1            |          |          |          | 2379.62     | 742.96  | 0.001345967          |
596         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
597         + acpi-cpufreq-ondemand                           | 2            |          |          |          | 441.74      | 817.49  | 0.001223256          |
598         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
599         + acpi-cpufreq-ondemand                           | 3            |          |          |          | 455.48      | 820.01  | 0.001219497          |
600         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
601         + acpi-cpufreq-ondemand                           | Average      |          |          |          | 425.613     | 793.487 | 0.001260260          |
602         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
603         + acpi-cpufreq-schedutil                          | 1            |          |          |          | 459.69      | 838.54  | 0.001192548          |
604         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
605         + acpi-cpufreq-schedutil                          | 2            |          |          |          | 466.55      | 830.89  | 0.001203528          |
606         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
607         + acpi-cpufreq-schedutil                          | 3            |          |          |          | 470.38      | 837.32  | 0.001194286          |
608         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
609         + acpi-cpufreq-schedutil                          | Average      |          |          |          | 465.54      | 835.583 | 0.001196769          |
610         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
611         + acpi-cpufreq-ondemand VS acpi-cpufreq-schedutil | Comprison(%) |          |          |          | 9.3810      | 5.3051  | -5.0379              |
612         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
613         + amd-pstate-ondemand VS amd-pstate-schedutil     | Comprison(%) | 124.7392 | -36.2934 | 140.7329 | 1.1081      | 2.0661  | -2.0242              |
614         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
615         + acpi-cpufreq-ondemand VS amd-pstate-ondemand    | Comprison(%) |          |          |          | 10.4665     | 7.5968  | -7.0605              |
616         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
617         + acpi-cpufreq-schedutil VS amd-pstate-schedutil  | Comprison(%) |          |          |          | 2.1115      | 4.2873  | -4.1110              |
618         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
619
620Reference
621===========
622
623.. [1] AMD64 Architecture Programmer's Manual Volume 2: System Programming,
624       https://www.amd.com/system/files/TechDocs/24593.pdf
625
626.. [2] Advanced Configuration and Power Interface Specification,
627       https://uefi.org/sites/default/files/resources/ACPI_Spec_6_4_Jan22.pdf
628
629.. [3] Processor Programming Reference (PPR) for AMD Family 19h Model 51h, Revision A1 Processors
630       https://www.amd.com/system/files/TechDocs/56569-A1-PUB.zip
631
632.. [4] Linux Kernel Selftests,
633       https://www.kernel.org/doc/html/latest/dev-tools/kselftest.html
634