[v5,0/6] amd_pstate: Add guided autonomous mode support

  From ACPI spec[1] below 3 modes for CPPC can be defined:
1. Non autonomous: OS scaling governor specifies operating frequency/
   performance level through `Desired Performance` register and platform
follows that.
2. Guided autonomous: OS scaling governor specifies min and max
   frequencies/ performance levels through `Minimum Performance` and
`Maximum Performance` register, and platform can autonomously select an
operating frequency in this range.
3. Fully autonomous: OS only hints (via EPP) to platform for the required
   energy performance preference for the workload and platform autonomously
scales the frequency.

Currently (1) is supported by amd_pstate as passive mode, and (3) is
implemented by EPP support[2]. This change is to support (2).

In guided autonomous mode the min_perf is based on the input from the
scaling governor. For example, in case of schedutil this value depends
on the current utilization. And max_perf is set to max capacity.

To activate guided auto mode ``amd_pstate=guided`` command line
parameter has to be passed in the kernel.

Below are the results (normalized) of benchmarks with this patch:
System: Genoa 96C 192T
Kernel: 6.2.0-rc2 + EPP v12 + patch
Scaling governor: schedutil

================ dbench comparisons ================
dbench result comparison:
Here results are throughput (MB/s)
Clients:   acpi-cpufreq		   amd_pst+passive	   amd_pst+guided
    1	   1.00 (0.00 pct)	   1.01 (1.00 pct)	   1.02 (2.00 pct)
    2	   1.07 (0.00 pct)	   1.06 (-0.93 pct)	   1.07 (0.00 pct)
    4	   1.68 (0.00 pct)	   1.70 (1.19 pct)	   1.72 (2.38 pct)
    8	   2.61 (0.00 pct)	   2.68 (2.68 pct)	   2.76 (5.74 pct)
   16	   4.16 (0.00 pct)	   4.24 (1.92 pct)	   4.53 (8.89 pct)
   32	   5.98 (0.00 pct)	   6.17 (3.17 pct)	   7.30 (22.07 pct)
   64	   8.67 (0.00 pct)	   8.99 (3.69 pct)	  10.71 (23.52 pct)
  128	  11.98 (0.00 pct)	  12.52 (4.50 pct)	  14.67 (22.45 pct)
  256	  15.73 (0.00 pct)	  16.13 (2.54 pct)	  17.81 (13.22 pct)
  512	  15.77 (0.00 pct)	  16.32 (3.48 pct)	  16.39 (3.93 pct)
dbench power comparison:
Clients:   acpi-cpufreq		   amd_pst+passive	   amd_pst+guided
    1	   1.00 (0.00 pct)	   1.00 (0.00 pct)	   1.04 (4.00 pct)
    2	   0.99 (0.00 pct)	   0.97 (-2.02 pct)	   1.02 (3.03 pct)
    4	   0.98 (0.00 pct)	   0.98 (0.00 pct)	   1.02 (4.08 pct)
    8	   0.98 (0.00 pct)	   0.99 (1.02 pct)	   1.02 (4.08 pct)
   16	   0.99 (0.00 pct)	   1.00 (1.01 pct)	   1.04 (5.05 pct)
   32	   1.02 (0.00 pct)	   1.02 (0.00 pct)	   1.07 (4.90 pct)
   64	   1.05 (0.00 pct)	   1.05 (0.00 pct)	   1.11 (5.71 pct)
  128	   1.08 (0.00 pct)	   1.08 (0.00 pct)	   1.15 (6.48 pct)
  256	   1.12 (0.00 pct)	   1.12 (0.00 pct)	   1.20 (7.14 pct)
  512	   1.18 (0.00 pct)	   1.17 (-0.84 pct)	   1.26 (6.77 pct)

================ git-source comparisons ================
git-source result comparison:
Here results are throughput (compilations per 1000 sec)
Threads:   acpi-cpufreq		   amd_pst+passive	   amd_pst+guided
  192	   1.00 (0.00 pct)	   0.93 (-7.00 pct)	   1.00 (0.00 pct)
git-source power comparison:
Threads:   acpi-cpufreq		   amd_pst+passive	   amd_pst+guided
  192	   1.00 (0.00 pct)	   1.00 (0.00 pct)	   0.96 (-4.00 pct)

================ kernbench comparisons ================
kernbench result comparison:
Here results are throughput (compilations per 1000 sec)
Load:	   acpi-cpufreq		   amd_pst+passive	   amd_pst+guided
32	   1.00 (0.00 pct)	   1.01 (1.00 pct)	   1.02 (2.00 pct)
48	   1.26 (0.00 pct)	   1.28 (1.58 pct)	   1.25 (-0.79 pct)
64	   1.39 (0.00 pct)	   1.47 (5.75 pct)	   1.43 (2.87 pct)
96	   1.48 (0.00 pct)	   1.50 (1.35 pct)	   1.49 (0.67 pct)
128	   1.29 (0.00 pct)	   1.32 (2.32 pct)	   1.33 (3.10 pct)
192	   1.17 (0.00 pct)	   1.20 (2.56 pct)	   1.21 (3.41 pct)
256	   1.17 (0.00 pct)	   1.18 (0.85 pct)	   1.20 (2.56 pct)
384	   1.16 (0.00 pct)	   1.17 (0.86 pct)	   1.21 (4.31 pct)
kernbench power comparison:
Clients:   acpi-cpufreq		   amd_pst+passive	   amd_pst+guided
   32	   1.00 (0.00 pct)	   0.97 (-3.00 pct)	   1.00 (0.00 pct)
   48	   0.87 (0.00 pct)	   0.81 (-6.89 pct)	   0.88 (1.14 pct)
   64	   0.81 (0.00 pct)	   0.73 (-9.87 pct)	   0.77 (-4.93 pct)
   96	   0.75 (0.00 pct)	   0.74 (-1.33 pct)	   0.75 (0.00 pct)
  128	   0.83 (0.00 pct)	   0.79 (-4.81 pct)	   0.83 (0.00 pct)
  192	   0.92 (0.00 pct)	   0.88 (-4.34 pct)	   0.92 (0.00 pct)
  256	   0.92 (0.00 pct)	   0.88 (-4.34 pct)	   0.92 (0.00 pct)
  384	   0.92 (0.00 pct)	   0.88 (-4.34 pct)	   0.92 (0.00 pct)

================ tbench comparisons ================
tbench result comparison:
Here results are throughput (MB/s)
Clients:   acpi-cpufreq		   amd_pst+passive	   amd_pst+guided
    1	   1.00 (0.00 pct)	   0.70 (-30.00 pct)	   1.37 (37.00 pct)
    2	   2.64 (0.00 pct)	   1.39 (-47.34 pct)	   2.70 (2.27 pct)
    4	   4.89 (0.00 pct)	   2.75 (-43.76 pct)	   5.28 (7.97 pct)
    8	   9.46 (0.00 pct)	   5.42 (-42.70 pct)	  10.22 (8.03 pct)
   16	  19.05 (0.00 pct)	  10.42 (-45.30 pct)	  19.94 (4.67 pct)
   32	  37.50 (0.00 pct)	  20.23 (-46.05 pct)	  36.87 (-1.68 pct)
   64	  61.24 (0.00 pct)	  43.08 (-29.65 pct)	  62.96 (2.80 pct)
  128	  67.16 (0.00 pct)	  69.08 (2.85 pct)	  67.34 (0.26 pct)
  256	 154.59 (0.00 pct)	 162.33 (5.00 pct)	 156.78 (1.41 pct)
  512	 154.02 (0.00 pct)	 156.74 (1.76 pct)	 153.48 (-0.35 pct)
tbench power comparison:
Clients:   acpi-cpufreq		   amd_pst+passive	   amd_pst+guided
    1	   1.00 (0.00 pct)	   0.97 (-3.00 pct)	   1.08 (8.00 pct)
    2	   1.04 (0.00 pct)	   0.97 (-6.73 pct)	   1.11 (6.73 pct)
    4	   1.12 (0.00 pct)	   0.99 (-11.60 pct)	   1.18 (5.35 pct)
    8	   1.25 (0.00 pct)	   1.04 (-16.80 pct)	   1.31 (4.80 pct)
   16	   1.53 (0.00 pct)	   1.13 (-26.14 pct)	   1.58 (3.26 pct)
   32	   2.01 (0.00 pct)	   1.36 (-32.33 pct)	   2.03 (0.99 pct)
   64	   2.58 (0.00 pct)	   2.14 (-17.05 pct)	   2.61 (1.16 pct)
  128	   2.80 (0.00 pct)	   2.81 (0.35 pct)	   2.81 (0.35 pct)
  256	   3.39 (0.00 pct)	   3.43 (1.17 pct)	   3.42 (0.88 pct)
  512	   3.44 (0.00 pct)	   3.44 (0.00 pct)	   3.44 (0.00 pct)

Note: this series is based on top of EPP v12 [3] series

Change log:

v4 -> v5:
- Rebased on top of EPP v12 series
- Addressed comments form Mario regarding documentation
- Picked up RB flags from Mario and Bagas Sanjaya

v3 -> v4:
- Fixed active mode low frequency issue reported by Peter Jung and Tor Vic
- Documentation modification suggested by Bagas Sanjaya

v2 -> v3:
- Addressed review comments form Mario.
- Picked up RB tag from Mario.
- Rebase on top of EPP v11 [3].

v1 -> v2:
- Fix issue with shared mem systems.
- Rebase on top of EPP series.

[1]: https://uefi.org/sites/default/files/resources/ACPI_6_3_final_Jan30.pdf
[2]: https://lore.kernel.org/lkml/20221110175847.3098728-1-Perry.Yuan@amd.com/
[3]: https://lore.kernel.org/linux-pm/20230131090016.3970625-1-perry.yuan@amd.com/

Wyes Karny (6):
  acpi: cppc: Add min and max perf reg writing support
  acpi: cppc: Add auto select register read/write support
  cpufreq: amd_pstate: Add guided autonomous mode
  Documentation: amd_pstate: Move amd_pstate param to alphabetical order
  cpufreq: amd_pstate: Add guided mode control support via sysfs
  Documentation: amd_pstate: Update amd_pstate status sysfs for guided

 .../admin-guide/kernel-parameters.txt         |  41 ++--
 Documentation/admin-guide/pm/amd-pstate.rst   |  34 +++-
 drivers/acpi/cppc_acpi.c                      | 121 +++++++++++-
 drivers/cpufreq/amd-pstate.c                  | 183 +++++++++++++-----
 include/acpi/cppc_acpi.h                      |  11 ++
 include/linux/amd-pstate.h                    |   2 +
 6 files changed, 311 insertions(+), 81 deletions(-)
  

On 01.02.23 06:58, Wyes Karny wrote:
>  From ACPI spec[1] below 3 modes for CPPC can be defined:
> 1. Non autonomous: OS scaling governor specifies operating frequency/
>     performance level through `Desired Performance` register and platform
> follows that.
> 2. Guided autonomous: OS scaling governor specifies min and max
>     frequencies/ performance levels through `Minimum Performance` and
> `Maximum Performance` register, and platform can autonomously select an
> operating frequency in this range.
> 3. Fully autonomous: OS only hints (via EPP) to platform for the required
>     energy performance preference for the workload and platform autonomously
> scales the frequency.
> 
> Currently (1) is supported by amd_pstate as passive mode, and (3) is
> implemented by EPP support[2]. This change is to support (2).
> 
> In guided autonomous mode the min_perf is based on the input from the
> scaling governor. For example, in case of schedutil this value depends
> on the current utilization. And max_perf is set to max capacity.
> 
> To activate guided auto mode ``amd_pstate=guided`` command line
> parameter has to be passed in the kernel.
> 
> Below are the results (normalized) of benchmarks with this patch:
> System: Genoa 96C 192T
> Kernel: 6.2.0-rc2 + EPP v12 + patch
> Scaling governor: schedutil
> 
> ================ dbench comparisons ================
> dbench result comparison:
> Here results are throughput (MB/s)
> Clients:   acpi-cpufreq		   amd_pst+passive	   amd_pst+guided
>      1	   1.00 (0.00 pct)	   1.01 (1.00 pct)	   1.02 (2.00 pct)
>      2	   1.07 (0.00 pct)	   1.06 (-0.93 pct)	   1.07 (0.00 pct)
>      4	   1.68 (0.00 pct)	   1.70 (1.19 pct)	   1.72 (2.38 pct)
>      8	   2.61 (0.00 pct)	   2.68 (2.68 pct)	   2.76 (5.74 pct)
>     16	   4.16 (0.00 pct)	   4.24 (1.92 pct)	   4.53 (8.89 pct)
>     32	   5.98 (0.00 pct)	   6.17 (3.17 pct)	   7.30 (22.07 pct)
>     64	   8.67 (0.00 pct)	   8.99 (3.69 pct)	  10.71 (23.52 pct)
>    128	  11.98 (0.00 pct)	  12.52 (4.50 pct)	  14.67 (22.45 pct)
>    256	  15.73 (0.00 pct)	  16.13 (2.54 pct)	  17.81 (13.22 pct)
>    512	  15.77 (0.00 pct)	  16.32 (3.48 pct)	  16.39 (3.93 pct)
> dbench power comparison:
> Clients:   acpi-cpufreq		   amd_pst+passive	   amd_pst+guided
>      1	   1.00 (0.00 pct)	   1.00 (0.00 pct)	   1.04 (4.00 pct)
>      2	   0.99 (0.00 pct)	   0.97 (-2.02 pct)	   1.02 (3.03 pct)
>      4	   0.98 (0.00 pct)	   0.98 (0.00 pct)	   1.02 (4.08 pct)
>      8	   0.98 (0.00 pct)	   0.99 (1.02 pct)	   1.02 (4.08 pct)
>     16	   0.99 (0.00 pct)	   1.00 (1.01 pct)	   1.04 (5.05 pct)
>     32	   1.02 (0.00 pct)	   1.02 (0.00 pct)	   1.07 (4.90 pct)
>     64	   1.05 (0.00 pct)	   1.05 (0.00 pct)	   1.11 (5.71 pct)
>    128	   1.08 (0.00 pct)	   1.08 (0.00 pct)	   1.15 (6.48 pct)
>    256	   1.12 (0.00 pct)	   1.12 (0.00 pct)	   1.20 (7.14 pct)
>    512	   1.18 (0.00 pct)	   1.17 (-0.84 pct)	   1.26 (6.77 pct)
> 
> ================ git-source comparisons ================
> git-source result comparison:
> Here results are throughput (compilations per 1000 sec)
> Threads:   acpi-cpufreq		   amd_pst+passive	   amd_pst+guided
>    192	   1.00 (0.00 pct)	   0.93 (-7.00 pct)	   1.00 (0.00 pct)
> git-source power comparison:
> Threads:   acpi-cpufreq		   amd_pst+passive	   amd_pst+guided
>    192	   1.00 (0.00 pct)	   1.00 (0.00 pct)	   0.96 (-4.00 pct)
> 
> ================ kernbench comparisons ================
> kernbench result comparison:
> Here results are throughput (compilations per 1000 sec)
> Load:	   acpi-cpufreq		   amd_pst+passive	   amd_pst+guided
> 32	   1.00 (0.00 pct)	   1.01 (1.00 pct)	   1.02 (2.00 pct)
> 48	   1.26 (0.00 pct)	   1.28 (1.58 pct)	   1.25 (-0.79 pct)
> 64	   1.39 (0.00 pct)	   1.47 (5.75 pct)	   1.43 (2.87 pct)
> 96	   1.48 (0.00 pct)	   1.50 (1.35 pct)	   1.49 (0.67 pct)
> 128	   1.29 (0.00 pct)	   1.32 (2.32 pct)	   1.33 (3.10 pct)
> 192	   1.17 (0.00 pct)	   1.20 (2.56 pct)	   1.21 (3.41 pct)
> 256	   1.17 (0.00 pct)	   1.18 (0.85 pct)	   1.20 (2.56 pct)
> 384	   1.16 (0.00 pct)	   1.17 (0.86 pct)	   1.21 (4.31 pct)
> kernbench power comparison:
> Clients:   acpi-cpufreq		   amd_pst+passive	   amd_pst+guided
>     32	   1.00 (0.00 pct)	   0.97 (-3.00 pct)	   1.00 (0.00 pct)
>     48	   0.87 (0.00 pct)	   0.81 (-6.89 pct)	   0.88 (1.14 pct)
>     64	   0.81 (0.00 pct)	   0.73 (-9.87 pct)	   0.77 (-4.93 pct)
>     96	   0.75 (0.00 pct)	   0.74 (-1.33 pct)	   0.75 (0.00 pct)
>    128	   0.83 (0.00 pct)	   0.79 (-4.81 pct)	   0.83 (0.00 pct)
>    192	   0.92 (0.00 pct)	   0.88 (-4.34 pct)	   0.92 (0.00 pct)
>    256	   0.92 (0.00 pct)	   0.88 (-4.34 pct)	   0.92 (0.00 pct)
>    384	   0.92 (0.00 pct)	   0.88 (-4.34 pct)	   0.92 (0.00 pct)
> 
> ================ tbench comparisons ================
> tbench result comparison:
> Here results are throughput (MB/s)
> Clients:   acpi-cpufreq		   amd_pst+passive	   amd_pst+guided
>      1	   1.00 (0.00 pct)	   0.70 (-30.00 pct)	   1.37 (37.00 pct)
>      2	   2.64 (0.00 pct)	   1.39 (-47.34 pct)	   2.70 (2.27 pct)
>      4	   4.89 (0.00 pct)	   2.75 (-43.76 pct)	   5.28 (7.97 pct)
>      8	   9.46 (0.00 pct)	   5.42 (-42.70 pct)	  10.22 (8.03 pct)
>     16	  19.05 (0.00 pct)	  10.42 (-45.30 pct)	  19.94 (4.67 pct)
>     32	  37.50 (0.00 pct)	  20.23 (-46.05 pct)	  36.87 (-1.68 pct)
>     64	  61.24 (0.00 pct)	  43.08 (-29.65 pct)	  62.96 (2.80 pct)
>    128	  67.16 (0.00 pct)	  69.08 (2.85 pct)	  67.34 (0.26 pct)
>    256	 154.59 (0.00 pct)	 162.33 (5.00 pct)	 156.78 (1.41 pct)
>    512	 154.02 (0.00 pct)	 156.74 (1.76 pct)	 153.48 (-0.35 pct)
> tbench power comparison:
> Clients:   acpi-cpufreq		   amd_pst+passive	   amd_pst+guided
>      1	   1.00 (0.00 pct)	   0.97 (-3.00 pct)	   1.08 (8.00 pct)
>      2	   1.04 (0.00 pct)	   0.97 (-6.73 pct)	   1.11 (6.73 pct)
>      4	   1.12 (0.00 pct)	   0.99 (-11.60 pct)	   1.18 (5.35 pct)
>      8	   1.25 (0.00 pct)	   1.04 (-16.80 pct)	   1.31 (4.80 pct)
>     16	   1.53 (0.00 pct)	   1.13 (-26.14 pct)	   1.58 (3.26 pct)
>     32	   2.01 (0.00 pct)	   1.36 (-32.33 pct)	   2.03 (0.99 pct)
>     64	   2.58 (0.00 pct)	   2.14 (-17.05 pct)	   2.61 (1.16 pct)
>    128	   2.80 (0.00 pct)	   2.81 (0.35 pct)	   2.81 (0.35 pct)
>    256	   3.39 (0.00 pct)	   3.43 (1.17 pct)	   3.42 (0.88 pct)
>    512	   3.44 (0.00 pct)	   3.44 (0.00 pct)	   3.44 (0.00 pct)
> 
> Note: this series is based on top of EPP v12 [3] series
> 
> Change log:
> 
> v4 -> v5:
> - Rebased on top of EPP v12 series
> - Addressed comments form Mario regarding documentation
> - Picked up RB flags from Mario and Bagas Sanjaya
> 
> v3 -> v4:
> - Fixed active mode low frequency issue reported by Peter Jung and Tor Vic
> - Documentation modification suggested by Bagas Sanjaya
> 
> v2 -> v3:
> - Addressed review comments form Mario.
> - Picked up RB tag from Mario.
> - Rebase on top of EPP v11 [3].
> 
> v1 -> v2:
> - Fix issue with shared mem systems.
> - Rebase on top of EPP series.
> 
> [1]: https://uefi.org/sites/default/files/resources/ACPI_6_3_final_Jan30.pdf
> [2]: https://lore.kernel.org/lkml/20221110175847.3098728-1-Perry.Yuan@amd.com/
> [3]: https://lore.kernel.org/linux-pm/20230131090016.3970625-1-perry.yuan@amd.com/
> 
> Wyes Karny (6):
>    acpi: cppc: Add min and max perf reg writing support
>    acpi: cppc: Add auto select register read/write support
>    cpufreq: amd_pstate: Add guided autonomous mode
>    Documentation: amd_pstate: Move amd_pstate param to alphabetical order
>    cpufreq: amd_pstate: Add guided mode control support via sysfs
>    Documentation: amd_pstate: Update amd_pstate status sysfs for guided
> 
>   .../admin-guide/kernel-parameters.txt         |  41 ++--
>   Documentation/admin-guide/pm/amd-pstate.rst   |  34 +++-
>   drivers/acpi/cppc_acpi.c                      | 121 +++++++++++-
>   drivers/cpufreq/amd-pstate.c                  | 183 +++++++++++++-----
>   include/acpi/cppc_acpi.h                      |  11 ++
>   include/linux/amd-pstate.h                    |   2 +
>   6 files changed, 311 insertions(+), 81 deletions(-)
> 

I tested "active" mode on a Zen2, using EPP v12 and this series on top.

Here is the output of 'cpupower frequency-info' run as root under full load:

   analyzing CPU 0:
     driver: amd_pstate_epp
     CPUs which run at the same hardware frequency: 0
     CPUs which need to have their frequency coordinated by software: 0
     maximum transition latency:  Cannot determine or is not supported.
     hardware limits: 550 MHz - 4.67 GHz
     available cpufreq governors: performance powersave
     current policy: frequency should be within 550 MHz and 4.67 GHz.
                   The governor "powersave" may decide which speed to use
                   within this range.
     current CPU frequency: Unable to call hardware
     current CPU frequency: 4.18 GHz (asserted by call to kernel)
     boost state support:
       Supported: yes
       Active: yes
       Boost States: 0
       Total States: 3
       Pstate-P0:  3800MHz
       Pstate-P1:  2800MHz
       Pstate-P2:  2200MHz

Changing EPP mode via sysfs works.

----

Live-switching to "guided" mode via sysfs also seems to work fine:

   analyzing CPU 0:
     driver: amd-pstate
     CPUs which run at the same hardware frequency: 0
     CPUs which need to have their frequency coordinated by software: 0
     maximum transition latency: 20.0 us
     hardware limits: 550 MHz - 4.67 GHz
     available cpufreq governors: ondemand powersave performance schedutil
     current policy: frequency should be within 550 MHz and 4.67 GHz.
                   The governor "ondemand" may decide which speed to use
                   within this range.
     current CPU frequency: Unable to call hardware
     current CPU frequency: 3.71 GHz (asserted by call to kernel)
     boost state support:
       Supported: yes
       Active: yes
       AMD PSTATE Highest Performance: 166. Maximum Frequency: 4.67 GHz.
       AMD PSTATE Nominal Performance: 135. Nominal Frequency: 3.80 GHz.
       AMD PSTATE Lowest Non-linear Performance: 62. Lowest Non-linear 
Frequency: 1.74 GHz.
     AMD PSTATE Lowest Performance: 20. Lowest Frequency: 550 MHz.

----

Seems to work fine so far.
Hope this helps.
I can test more in detail and give you a Tested-by tag if wanted.

Thanks,

Tor Vic
  

Hi Tor Vic,

On 01 Feb 18:35, Tor Vic wrote:
> 
> On 01.02.23 06:58, Wyes Karny wrote:
> >  From ACPI spec[1] below 3 modes for CPPC can be defined:
> > 1. Non autonomous: OS scaling governor specifies operating frequency/
> >     performance level through `Desired Performance` register and platform
> > follows that.
> > 2. Guided autonomous: OS scaling governor specifies min and max
> >     frequencies/ performance levels through `Minimum Performance` and
> > `Maximum Performance` register, and platform can autonomously select an
> > operating frequency in this range.
> > 3. Fully autonomous: OS only hints (via EPP) to platform for the required
> >     energy performance preference for the workload and platform autonomously
> > scales the frequency.
> > 
> > Currently (1) is supported by amd_pstate as passive mode, and (3) is
> > implemented by EPP support[2]. This change is to support (2).
> > 
> > In guided autonomous mode the min_perf is based on the input from the
> > scaling governor. For example, in case of schedutil this value depends
> > on the current utilization. And max_perf is set to max capacity.
> > 
> > To activate guided auto mode ``amd_pstate=guided`` command line
> > parameter has to be passed in the kernel.
> > 
> > Below are the results (normalized) of benchmarks with this patch:
> > System: Genoa 96C 192T
> > Kernel: 6.2.0-rc2 + EPP v12 + patch
> > Scaling governor: schedutil
> > 
> > ================ dbench comparisons ================
> > dbench result comparison:
> > Here results are throughput (MB/s)
> > Clients:   acpi-cpufreq		   amd_pst+passive	   amd_pst+guided
> >      1	   1.00 (0.00 pct)	   1.01 (1.00 pct)	   1.02 (2.00 pct)
> >      2	   1.07 (0.00 pct)	   1.06 (-0.93 pct)	   1.07 (0.00 pct)
> >      4	   1.68 (0.00 pct)	   1.70 (1.19 pct)	   1.72 (2.38 pct)
> >      8	   2.61 (0.00 pct)	   2.68 (2.68 pct)	   2.76 (5.74 pct)
> >     16	   4.16 (0.00 pct)	   4.24 (1.92 pct)	   4.53 (8.89 pct)
> >     32	   5.98 (0.00 pct)	   6.17 (3.17 pct)	   7.30 (22.07 pct)
> >     64	   8.67 (0.00 pct)	   8.99 (3.69 pct)	  10.71 (23.52 pct)
> >    128	  11.98 (0.00 pct)	  12.52 (4.50 pct)	  14.67 (22.45 pct)
> >    256	  15.73 (0.00 pct)	  16.13 (2.54 pct)	  17.81 (13.22 pct)
> >    512	  15.77 (0.00 pct)	  16.32 (3.48 pct)	  16.39 (3.93 pct)
> > dbench power comparison:
> > Clients:   acpi-cpufreq		   amd_pst+passive	   amd_pst+guided
> >      1	   1.00 (0.00 pct)	   1.00 (0.00 pct)	   1.04 (4.00 pct)
> >      2	   0.99 (0.00 pct)	   0.97 (-2.02 pct)	   1.02 (3.03 pct)
> >      4	   0.98 (0.00 pct)	   0.98 (0.00 pct)	   1.02 (4.08 pct)
> >      8	   0.98 (0.00 pct)	   0.99 (1.02 pct)	   1.02 (4.08 pct)
> >     16	   0.99 (0.00 pct)	   1.00 (1.01 pct)	   1.04 (5.05 pct)
> >     32	   1.02 (0.00 pct)	   1.02 (0.00 pct)	   1.07 (4.90 pct)
> >     64	   1.05 (0.00 pct)	   1.05 (0.00 pct)	   1.11 (5.71 pct)
> >    128	   1.08 (0.00 pct)	   1.08 (0.00 pct)	   1.15 (6.48 pct)
> >    256	   1.12 (0.00 pct)	   1.12 (0.00 pct)	   1.20 (7.14 pct)
> >    512	   1.18 (0.00 pct)	   1.17 (-0.84 pct)	   1.26 (6.77 pct)
> > 
> > ================ git-source comparisons ================
> > git-source result comparison:
> > Here results are throughput (compilations per 1000 sec)
> > Threads:   acpi-cpufreq		   amd_pst+passive	   amd_pst+guided
> >    192	   1.00 (0.00 pct)	   0.93 (-7.00 pct)	   1.00 (0.00 pct)
> > git-source power comparison:
> > Threads:   acpi-cpufreq		   amd_pst+passive	   amd_pst+guided
> >    192	   1.00 (0.00 pct)	   1.00 (0.00 pct)	   0.96 (-4.00 pct)
> > 
> > ================ kernbench comparisons ================
> > kernbench result comparison:
> > Here results are throughput (compilations per 1000 sec)
> > Load:	   acpi-cpufreq		   amd_pst+passive	   amd_pst+guided
> > 32	   1.00 (0.00 pct)	   1.01 (1.00 pct)	   1.02 (2.00 pct)
> > 48	   1.26 (0.00 pct)	   1.28 (1.58 pct)	   1.25 (-0.79 pct)
> > 64	   1.39 (0.00 pct)	   1.47 (5.75 pct)	   1.43 (2.87 pct)
> > 96	   1.48 (0.00 pct)	   1.50 (1.35 pct)	   1.49 (0.67 pct)
> > 128	   1.29 (0.00 pct)	   1.32 (2.32 pct)	   1.33 (3.10 pct)
> > 192	   1.17 (0.00 pct)	   1.20 (2.56 pct)	   1.21 (3.41 pct)
> > 256	   1.17 (0.00 pct)	   1.18 (0.85 pct)	   1.20 (2.56 pct)
> > 384	   1.16 (0.00 pct)	   1.17 (0.86 pct)	   1.21 (4.31 pct)
> > kernbench power comparison:
> > Clients:   acpi-cpufreq		   amd_pst+passive	   amd_pst+guided
> >     32	   1.00 (0.00 pct)	   0.97 (-3.00 pct)	   1.00 (0.00 pct)
> >     48	   0.87 (0.00 pct)	   0.81 (-6.89 pct)	   0.88 (1.14 pct)
> >     64	   0.81 (0.00 pct)	   0.73 (-9.87 pct)	   0.77 (-4.93 pct)
> >     96	   0.75 (0.00 pct)	   0.74 (-1.33 pct)	   0.75 (0.00 pct)
> >    128	   0.83 (0.00 pct)	   0.79 (-4.81 pct)	   0.83 (0.00 pct)
> >    192	   0.92 (0.00 pct)	   0.88 (-4.34 pct)	   0.92 (0.00 pct)
> >    256	   0.92 (0.00 pct)	   0.88 (-4.34 pct)	   0.92 (0.00 pct)
> >    384	   0.92 (0.00 pct)	   0.88 (-4.34 pct)	   0.92 (0.00 pct)
> > 
> > ================ tbench comparisons ================
> > tbench result comparison:
> > Here results are throughput (MB/s)
> > Clients:   acpi-cpufreq		   amd_pst+passive	   amd_pst+guided
> >      1	   1.00 (0.00 pct)	   0.70 (-30.00 pct)	   1.37 (37.00 pct)
> >      2	   2.64 (0.00 pct)	   1.39 (-47.34 pct)	   2.70 (2.27 pct)
> >      4	   4.89 (0.00 pct)	   2.75 (-43.76 pct)	   5.28 (7.97 pct)
> >      8	   9.46 (0.00 pct)	   5.42 (-42.70 pct)	  10.22 (8.03 pct)
> >     16	  19.05 (0.00 pct)	  10.42 (-45.30 pct)	  19.94 (4.67 pct)
> >     32	  37.50 (0.00 pct)	  20.23 (-46.05 pct)	  36.87 (-1.68 pct)
> >     64	  61.24 (0.00 pct)	  43.08 (-29.65 pct)	  62.96 (2.80 pct)
> >    128	  67.16 (0.00 pct)	  69.08 (2.85 pct)	  67.34 (0.26 pct)
> >    256	 154.59 (0.00 pct)	 162.33 (5.00 pct)	 156.78 (1.41 pct)
> >    512	 154.02 (0.00 pct)	 156.74 (1.76 pct)	 153.48 (-0.35 pct)
> > tbench power comparison:
> > Clients:   acpi-cpufreq		   amd_pst+passive	   amd_pst+guided
> >      1	   1.00 (0.00 pct)	   0.97 (-3.00 pct)	   1.08 (8.00 pct)
> >      2	   1.04 (0.00 pct)	   0.97 (-6.73 pct)	   1.11 (6.73 pct)
> >      4	   1.12 (0.00 pct)	   0.99 (-11.60 pct)	   1.18 (5.35 pct)
> >      8	   1.25 (0.00 pct)	   1.04 (-16.80 pct)	   1.31 (4.80 pct)
> >     16	   1.53 (0.00 pct)	   1.13 (-26.14 pct)	   1.58 (3.26 pct)
> >     32	   2.01 (0.00 pct)	   1.36 (-32.33 pct)	   2.03 (0.99 pct)
> >     64	   2.58 (0.00 pct)	   2.14 (-17.05 pct)	   2.61 (1.16 pct)
> >    128	   2.80 (0.00 pct)	   2.81 (0.35 pct)	   2.81 (0.35 pct)
> >    256	   3.39 (0.00 pct)	   3.43 (1.17 pct)	   3.42 (0.88 pct)
> >    512	   3.44 (0.00 pct)	   3.44 (0.00 pct)	   3.44 (0.00 pct)
> > 
> > Note: this series is based on top of EPP v12 [3] series
> > 
> > Change log:
> > 
> > v4 -> v5:
> > - Rebased on top of EPP v12 series
> > - Addressed comments form Mario regarding documentation
> > - Picked up RB flags from Mario and Bagas Sanjaya
> > 
> > v3 -> v4:
> > - Fixed active mode low frequency issue reported by Peter Jung and Tor Vic
> > - Documentation modification suggested by Bagas Sanjaya
> > 
> > v2 -> v3:
> > - Addressed review comments form Mario.
> > - Picked up RB tag from Mario.
> > - Rebase on top of EPP v11 [3].
> > 
> > v1 -> v2:
> > - Fix issue with shared mem systems.
> > - Rebase on top of EPP series.
> > 
> > [1]: https://uefi.org/sites/default/files/resources/ACPI_6_3_final_Jan30.pdf
> > [2]: https://lore.kernel.org/lkml/20221110175847.3098728-1-Perry.Yuan@amd.com/
> > [3]: https://lore.kernel.org/linux-pm/20230131090016.3970625-1-perry.yuan@amd.com/
> > 
> > Wyes Karny (6):
> >    acpi: cppc: Add min and max perf reg writing support
> >    acpi: cppc: Add auto select register read/write support
> >    cpufreq: amd_pstate: Add guided autonomous mode
> >    Documentation: amd_pstate: Move amd_pstate param to alphabetical order
> >    cpufreq: amd_pstate: Add guided mode control support via sysfs
> >    Documentation: amd_pstate: Update amd_pstate status sysfs for guided
> > 
> >   .../admin-guide/kernel-parameters.txt         |  41 ++--
> >   Documentation/admin-guide/pm/amd-pstate.rst   |  34 +++-
> >   drivers/acpi/cppc_acpi.c                      | 121 +++++++++++-
> >   drivers/cpufreq/amd-pstate.c                  | 183 +++++++++++++-----
> >   include/acpi/cppc_acpi.h                      |  11 ++
> >   include/linux/amd-pstate.h                    |   2 +
> >   6 files changed, 311 insertions(+), 81 deletions(-)
> > 
> 
> I tested "active" mode on a Zen2, using EPP v12 and this series on top.
> 
> Here is the output of 'cpupower frequency-info' run as root under full load:
> 
>   analyzing CPU 0:
>     driver: amd_pstate_epp
>     CPUs which run at the same hardware frequency: 0
>     CPUs which need to have their frequency coordinated by software: 0
>     maximum transition latency:  Cannot determine or is not supported.
>     hardware limits: 550 MHz - 4.67 GHz
>     available cpufreq governors: performance powersave
>     current policy: frequency should be within 550 MHz and 4.67 GHz.
>                   The governor "powersave" may decide which speed to use
>                   within this range.
>     current CPU frequency: Unable to call hardware
>     current CPU frequency: 4.18 GHz (asserted by call to kernel)
>     boost state support:
>       Supported: yes
>       Active: yes
>       Boost States: 0
>       Total States: 3
>       Pstate-P0:  3800MHz
>       Pstate-P1:  2800MHz
>       Pstate-P2:  2200MHz
> 
> Changing EPP mode via sysfs works.
> 
> ----
> 
> Live-switching to "guided" mode via sysfs also seems to work fine:
> 
>   analyzing CPU 0:
>     driver: amd-pstate
>     CPUs which run at the same hardware frequency: 0
>     CPUs which need to have their frequency coordinated by software: 0
>     maximum transition latency: 20.0 us
>     hardware limits: 550 MHz - 4.67 GHz
>     available cpufreq governors: ondemand powersave performance schedutil
>     current policy: frequency should be within 550 MHz and 4.67 GHz.
>                   The governor "ondemand" may decide which speed to use
>                   within this range.
>     current CPU frequency: Unable to call hardware
>     current CPU frequency: 3.71 GHz (asserted by call to kernel)
>     boost state support:
>       Supported: yes
>       Active: yes
>       AMD PSTATE Highest Performance: 166. Maximum Frequency: 4.67 GHz.
>       AMD PSTATE Nominal Performance: 135. Nominal Frequency: 3.80 GHz.
>       AMD PSTATE Lowest Non-linear Performance: 62. Lowest Non-linear
> Frequency: 1.74 GHz.
>     AMD PSTATE Lowest Performance: 20. Lowest Frequency: 550 MHz.
> 
> ----
> 
> Seems to work fine so far.
> Hope this helps.
> I can test more in detail and give you a Tested-by tag if wanted.

Thanks for testing this. Please feel free to add Tested-by tag after your
testing done.

Thanks,
Wyes
> 
> Thanks,
> 
> Tor Vic