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Date: Tue, 29 Nov 2022 19:19:00 +0000
From: Tor Vic <torvic9@...lbox.org>
To: Perry Yuan <perry.yuan@....com>, rafael.j.wysocki@...el.com,
Mario.Limonciello@....com, ray.huang@....com,
viresh.kumar@...aro.org
Cc: Deepak.Sharma@....com, Nathan.Fontenot@....com,
Alexander.Deucher@....com, Shimmer.Huang@....com,
Xiaojian.Du@....com, Li.Meng@....com, wyes.karny@....com,
linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 0/9] Implement AMD Pstate EPP Driver
On 28.11.22 17:03, Perry Yuan wrote:
> Hi all,
>
> This patchset implements one new AMD CPU frequency driver
> "amd-pstate-epp” instance for better performance and power control.
> CPPC has a parameter called energy preference performance (EPP).
> The EPP is used in the CCLK DPM controller to drive the frequency that a core
> is going to operate during short periods of activity.
> EPP values will be utilized for different OS profiles (balanced, performance, power savings).
Hi,
what is the correct way to use this?
On my Zen2 machine, I passed "amd_pstate=active" to my cmdline, which
seems to work correctly according to the following cpupower output:
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: 550 MHz (asserted by call to kernel)
boost state support:
Supported: yes
Active: no
(above was in idle state - under full load I get the expected 4.1-4.2 GHz)
But is it correct that it uses the "powersave" governor?
If I try to change the governor with
sudo $PATHTOEXEC/cpupower frequency-set -g schedutil
I will get an error (ondemand and schedutil are built-in):
Setting cpu: 0
Error setting new values. Common errors:
- Do you have proper administration rights? (super-user?)
- Is the governor you requested available and modprobed?
- Trying to set an invalid policy?
- Trying to set a specific frequency, but userspace governor is not
available,
for example because of hardware which cannot be set to a specific
frequency
or because the userspace governor isn't loaded?
Maybe this should be clarified in more detail.
Cheers,
Tor Vic
>
> AMD Energy Performance Preference (EPP) provides a hint to the hardware
> if software wants to bias toward performance (0x0) or energy efficiency (0xff)
> The lowlevel power firmware will calculate the runtime frequency according to the EPP preference
> value. So the EPP hint will impact the CPU cores frequency responsiveness.
>
> We use the RAPL interface with "perf" tool to get the energy data of the package power.
> Performance Per Watt (PPW) Calculation:
>
> The PPW calculation is referred by below paper:
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsoftware.intel.com%2Fcontent%2Fdam%2Fdevelop%2Fexternal%2Fus%2Fen%2Fdocuments%2Fperformance-per-what-paper.pdf&data=04%7C01%7CPerry.Yuan%40amd.com%7Cac66e8ce98044e9b062708d9ab47c8d8%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637729147708574423%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=TPOvCE%2Frbb0ptBreWNxHqOi9YnVhcHGKG88vviDLb00%3D&reserved=0
>
> Below formula is referred from below spec to measure the PPW:
>
> (F / t) / P = F * t / (t * E) = F / E,
>
> "F" is the number of frames per second.
> "P" is power measured in watts.
> "E" is energy measured in joules.
>
> Gitsouce Benchmark Data on ROME Server CPU
> +------------------------------+------------------------------+------------+------------------+
> | Kernel Module | PPW (1 / s * J) |Energy(J) | PPW Improvement (%)|
> +==============================+==============================+============+==================+
> | acpi-cpufreq:schedutil | 5.85658E-05 | 17074.8 | base |
> +------------------------------+------------------------------+------------+------------------+
> | acpi-cpufreq:ondemand | 5.03079E-05 | 19877.6 | -14.10% |
> +------------------------------+------------------------------+------------+------------------+
> | acpi-cpufreq:performance | 5.88132E-05 | 17003 | 0.42% |
> +------------------------------+------------------------------+------------+------------------+
> | amd-pstate:ondemand | 4.60295E-05 | 21725.2 | -21.41% |
> +------------------------------+------------------------------+------------+------------------+
> | amd-pstate:schedutil | 4.70026E-05 | 21275.4 | -19.7% |
> +------------------------------+------------------------------+------------+------------------+
> | amd-pstate:performance | 5.80094E-05 | 17238.6 | -0.95% |
> +------------------------------+------------------------------+------------+------------------+
> | EPP:performance | 5.8292E-05 | 17155 | -0.47% |
> +------------------------------+------------------------------+------------+------------------+
> | EPP: balance performance: | 6.71709E-05 | 14887.4 | 14.69% |
> +------------------------------+------------------------------+------------+------------------+
> | EPP:power | 6.66951E-05 | 4993.6 | 13.88% |
> +------------------------------+------------------------------+------------+------------------+
>
> Tbench Benchmark Data on ROME Server CPU
> +---------------------------------------------+-------------------+--------------+-------------+------------------+
> | Kernel Module | PPW MB / (s * J) |Throughput(MB/s)| Energy (J)|PPW Improvement(%)|
> +=============================================+===================+==============+=============+==================+
> | acpi_cpufreq: schedutil | 46.39 | 17191 | 37057.3 | base |
> +---------------------------------------------+-------------------+--------------+-------------+------------------+
> | acpi_cpufreq: ondemand | 51.51 | 19269.5 | 37406.5 | 11.04 % |
> +---------------------------------------------+-------------------+--------------+-------------+------------------+
> | acpi_cpufreq: performance | 45.96 | 17063.7 | 37123.7 | -0.74 % |
> +---------------------------------------------+-------------------+--------------+-------------+------------------+
> | EPP:powersave: performance(0) | 54.46 | 20263.1 | 37205 | 17.87 % |
> +---------------------------------------------+-------------------+--------------+-------------+------------------+
> | EPP:powersave: balance performance | 55.03 | 20481.9 | 37221.5 | 19.14 % |
> +---------------------------------------------+-------------------+--------------+-------------+------------------+
> | EPP:powersave: balance_power | 54.43 | 20245.9 | 37194.2 | 17.77 % |
> +---------------------------------------------+-------------------+--------------+-------------+------------------+
> | EPP:powersave: power(255) | 54.26 | 20181.7 | 37197.4 | 17.40 % |
> +---------------------------------------------+-------------------+--------------+-------------+------------------+
> | amd-pstate: schedutil | 48.22 | 17844.9 | 37006.6 | 3.80 % |
> +---------------------------------------------+-------------------+--------------+-------------+------------------+
> | amd-pstate: ondemand | 61.30 | 22988 | 37503.4 | 33.72 % |
> +---------------------------------------------+-------------------+--------------+-------------+------------------+
> | amd-pstate: performance | 54.52 | 20252.6 | 37147.8 | 17.81 % |
> +---------------------------------------------+-------------------+--------------+-------------+------------------+
>
> changes from v4:
> * rebase driver based on the v6.1-rc7
> * remove the builtin changes patch because pstate driver has been
> changed to builtin type by another thread patch
> * update Documentation: amd-pstate: add amd pstate driver mode introduction
> * replace sprintf with sysfs_emit() instead.
> * fix typo for cppc_set_epp_perf() in cppc_acpi.h header
>
> changes from v3:
> * add one more document update patch for the active and passive mode
> introducion.
> * drive most of the feedbacks from Mario
> * drive feedback from Rafael for the cppc_acpi driver.
> * remove the epp raw data set/get function
> * set the amd-pstate drive by passing kernel parameter
> * set amd-pstate driver disabled by default if no kernel parameter
> input from booting
> * get cppc_set_auto_epp and cppc_set_epp_perf combined
> * pick up reviewed by flag from Mario
>
> changes from v2:
> * change pstate driver as builtin type from module
> * drop patch "export cpufreq cpu release and acquire"
> * squash patch of shared mem into single patch of epp implementation
> * add one new patch to support frequency boost control
> * add patch to expose driver working status checking
> * rebase driver into v6.1-rc4 kernel release
> * move some declaration to amd-pstate.h
> * drive feedback from Mario for the online/offline patch
> * drive feedback from Mario for the suspend/resume patch
> * drive feedback from Ray for the cppc_acpi and some other patches
> * drive feedback from Nathan for the epp patch
>
> changes from v1:
> * rebased to v6.0
> * drive feedbacks from Mario for the suspend/resume patch
> * drive feedbacks from Nathan for the EPP support on msr type
> * fix some typos and code style indent problems
> * update commit comments for patch 4/7
> * change the `epp_enabled` module param name to `epp`
> * set the default epp mode to be false
> * add testing for the x86_energy_perf_policy utility patchset(will
> send that utility patchset with another thread)
>
> v4: https://lore.kernel.org/lkml/20221110175847.3098728-1-Perry.Yuan@amd.com/
> v3: https://lore.kernel.org/all/20221107175705.2207842-1-Perry.Yuan@amd.com/
> v2: https://lore.kernel.org/all/20221010162248.348141-1-Perry.Yuan@amd.com/
> v1: https://lore.kernel.org/all/20221009071033.21170-1-Perry.Yuan@amd.com/
>
> Perry Yuan (9):
> ACPI: CPPC: Add AMD pstate energy performance preference cppc control
> Documentation: amd-pstate: add EPP profiles introduction
> cpufreq: amd_pstate: implement Pstate EPP support for the AMD
> processors
> cpufreq: amd_pstate: implement amd pstate cpu online and offline
> callback
> cpufreq: amd-pstate: implement suspend and resume callbacks
> cpufreq: amd-pstate: add frequency dynamic boost sysfs control
> cpufreq: amd_pstate: add driver working mode status sysfs entry
> Documentation: amd-pstate: add amd pstate driver mode introduction
> Documentation: introduce amd pstate active mode kernel command line
> options
>
> .../admin-guide/kernel-parameters.txt | 7 +
> Documentation/admin-guide/pm/amd-pstate.rst | 45 +-
> drivers/acpi/cppc_acpi.c | 114 ++-
> drivers/cpufreq/amd-pstate.c | 872 +++++++++++++++++-
> include/acpi/cppc_acpi.h | 12 +
> include/linux/amd-pstate.h | 82 ++
> 6 files changed, 1118 insertions(+), 14 deletions(-)
>
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