Re: [PATCH v3 0/6] amd_pstate: Add guided autonomous mode support

Huang Rui
2023-01-20T09:19:29Z

On Thu, Jan 19, 2023 at 07:50:11PM +0800, Karny, Wyes 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 v11 + 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 v11 [3] series
>
> Change log:
>
> 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/20230118075210.447418-1-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
>

Wyes, thanks for the patches. I will take a look at them after Chinese new
year.

Thanks,
Ray