Re: [PATCH v5 0/6] amd_pstate: Add guided autonomous mode support
From: Wyes Karny
Date: Wed Feb 01 2023 - 23:47:10 EST
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@xxxxxxx/
> > [3]: https://lore.kernel.org/linux-pm/20230131090016.3970625-1-perry.yuan@xxxxxxx/
> >
> > 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