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Documentation/amd-pstate: Add documentation for amd_pstate_floor_{freq,count}

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Add documentation for the sysfs files
/sys/devices/system/cpu/cpufreq/policy*/amd_pstate_floor_freq
and
/sys/devices/system/cpu/cpufreq/policy*/amd_pstate_floor_count.

Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Signed-off-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
This commit is contained in:
Gautham R. Shenoy
2026-03-26 17:17:56 +05:30
committed by Mario Limonciello (AMD)
parent a5bc4c44ae
commit 88d2ca6a68
1 changed files with 32 additions and 0 deletions
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Documentation/admin-guide/pm/amd-pstate.rst
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@@ -242,6 +242,8 @@ control its functionality at the system level. They are located in the
/sys/devices/system/cpu/cpufreq/policy0/amd_pstate_hw_prefcore
/sys/devices/system/cpu/cpufreq/policy0/amd_pstate_lowest_nonlinear_freq
/sys/devices/system/cpu/cpufreq/policy0/amd_pstate_max_freq
/sys/devices/system/cpu/cpufreq/policy0/amd_pstate_floor_freq
/sys/devices/system/cpu/cpufreq/policy0/amd_pstate_floor_count
/sys/devices/system/cpu/cpufreq/policy0/amd_pstate_prefcore_ranking
@@ -277,6 +279,36 @@ larger numbers are preferred at the time of reading. This can change at
runtime based on platform conditions. This attribute is read-only. This file
is only visible on platforms which support the preferred core feature.
``amd_pstate_floor_freq``
The floor frequency associated with each CPU. Userspace can write any
value between ``cpuinfo_min_freq`` and ``scaling_max_freq`` into this
file. When the system is under power or thermal constraints, the
platform firmware will attempt to throttle the CPU frequency to the
value specified in ``amd_pstate_floor_freq`` before throttling it
further. This allows userspace to specify different floor frequencies
to different CPUs. For optimal results, threads of the same core
should have the same floor frequency value. This file is only visible
on platforms that support the CPPC Performance Priority feature.
``amd_pstate_floor_count``
The number of distinct Floor Performance levels supported by the
platform. For example, if this value is 2, then the number of unique
values obtained from the command ``cat
/sys/devices/system/cpu/cpufreq/policy*/amd_pstate_floor_freq |
sort -n | uniq`` should be at most this number for the behavior
described in ``amd_pstate_floor_freq`` to take effect. A zero value
implies that the platform supports unlimited floor performance levels.
This file is only visible on platforms that support the CPPC
Performance Priority feature.
**Note**: When ``amd_pstate_floor_count`` is non-zero, the frequency to
which the CPU is throttled under power or thermal constraints is
undefined when the number of unique values of ``amd_pstate_floor_freq``
across all CPUs in the system exceeds ``amd_pstate_floor_count``.
``energy_performance_available_preferences``
A list of all the supported EPP preferences that could be used for