Date:   Mon, 20 Mar 2023 10:10:04 +0530
From:   Wyes Karny <wyes.karny@amd.com>
To:     "Rafael J. Wysocki" <rafael@kernel.org>
Cc:     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>
Subject: Re: [PATCH v8 0/6] cpufreq: amd-pstate: Add guided autonomous mode
 support
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References: <20230307112740.132338-1-wyes.karny@amd.com>
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Hi Rafael,

On 17 Mar 19:10, Rafael J. Wysocki wrote:
> 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!

Thank you for taking this patch series.

Regards,
Wyes

> 
> > 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
> >