Re: [PATCH v5 0/6] amd_pstate: Add guided autonomous mode support
From: Tor Vic
Date: Wed Feb 01 2023 - 13:35:26 EST
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,
Tor Vic