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References: <20230307112740.132338-1-wyes.karny@amd.com>
In-Reply-To: <20230307112740.132338-1-wyes.karny@amd.com>
From:   "Rafael J. Wysocki" <rafael@kernel.org>
Date:   Fri, 17 Mar 2023 19:10:46 +0100
Message-ID: <CAJZ5v0gijQJeCpxgTOD6uj9Cjn8=C+FwX5Ub1SP3xe6ygCaX4Q@mail.gmail.com>
Subject: Re: [PATCH v8 0/6] cpufreq: amd-pstate: Add guided autonomous mode support
To:     Wyes Karny <wyes.karny@amd.com>
Cc:     Rafael J Wysocki <rafael@kernel.org>,
        Huang Rui <ray.huang@amd.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        Mario.Limonciello@amd.com, Perry.Yuan@amd.com,
        linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-pm@vger.kernel.org, Bagas Sanjaya <bagasdotme@gmail.com>,
        santosh.shukla@amd.com, Len Brown <lenb@kernel.org>,
        Robert Moore <robert.moore@intel.com>,
        Borislav Petkov <bp@alien8.de>,
        Ananth Narayan <ananth.narayan@amd.com>,
        gautham.shenoy@amd.com, Tor Vic <torvic9@mailbox.org>,
        Russell Haley <yumpusamongus@gmail.com>
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On Tue, Mar 7, 2023 at 12:28 PM Wyes Karny <wyes.karny@amd.com> 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: 6.3-rc1 + 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)
>
> Change log:
>
> v7 -> v8:
> - Rebased on top of 6.3-rc1 tip
> - Pickup tested-by flag by Oleksandr

This series has been applied as 6.4 material, but I generally prefer
ACPI and CPPC to be spelled in capitals in patch subjects and you
should be more careful about comments and white space added by your
patches (I have fixed up a few assorted issues of these types in the
patches).

Thanks!

> v6 -> v7:
> - Addressed comments by Ray
> - Reorder and rebase patches
> - Pick up Ack by Ray
>
> v5 -> v6:
> - Don't return -EBUSY when changing to same mode
>
> 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
>   Documentation: cpufreq: amd-pstate: Move amd_pstate param to
>     alphabetical order
>   cpufreq: amd-pstate: Add guided autonomous mode
>   cpufreq: amd-pstate: Add guided mode control support via sysfs
>   Documentation: cpufreq: amd-pstate: Update amd_pstate status sysfs for
>     guided
>
>  .../admin-guide/kernel-parameters.txt         |  40 ++--
>  Documentation/admin-guide/pm/amd-pstate.rst   |  31 ++-
>  drivers/acpi/cppc_acpi.c                      | 121 +++++++++++-
>  drivers/cpufreq/amd-pstate.c                  | 177 +++++++++++++-----
>  include/acpi/cppc_acpi.h                      |  11 ++
>  include/linux/amd-pstate.h                    |   2 +
>  6 files changed, 302 insertions(+), 80 deletions(-)
>
> --
> 2.34.1
>