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Documentation/amd-pstate: Add documentation for amd_pstate_floor_{freq,count}
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>
authored by
Gautham R. Shenoy
and committed by
Mario Limonciello (AMD)
88d2ca6a
a5bc4c44
+32
+32
Documentation/admin-guide/pm/amd-pstate.rst
+32
Documentation/admin-guide/pm/amd-pstate.rst
···
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/sys/devices/system/cpu/cpufreq/policy0/amd_pstate_hw_prefcore
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/sys/devices/system/cpu/cpufreq/policy0/amd_pstate_lowest_nonlinear_freq
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/sys/devices/system/cpu/cpufreq/policy0/amd_pstate_max_freq
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+
/sys/devices/system/cpu/cpufreq/policy0/amd_pstate_floor_freq
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+
/sys/devices/system/cpu/cpufreq/policy0/amd_pstate_floor_count
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/sys/devices/system/cpu/cpufreq/policy0/amd_pstate_prefcore_ranking
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···
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larger numbers are preferred at the time of reading. This can change at
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runtime based on platform conditions. This attribute is read-only. This file
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is only visible on platforms which support the preferred core feature.
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+
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``amd_pstate_floor_freq``
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The floor frequency associated with each CPU. Userspace can write any
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value between ``cpuinfo_min_freq`` and ``scaling_max_freq`` into this
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file. When the system is under power or thermal constraints, the
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platform firmware will attempt to throttle the CPU frequency to the
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value specified in ``amd_pstate_floor_freq`` before throttling it
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further. This allows userspace to specify different floor frequencies
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to different CPUs. For optimal results, threads of the same core
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should have the same floor frequency value. This file is only visible
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on platforms that support the CPPC Performance Priority feature.
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``amd_pstate_floor_count``
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The number of distinct Floor Performance levels supported by the
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platform. For example, if this value is 2, then the number of unique
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values obtained from the command ``cat
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/sys/devices/system/cpu/cpufreq/policy*/amd_pstate_floor_freq |
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sort -n | uniq`` should be at most this number for the behavior
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described in ``amd_pstate_floor_freq`` to take effect. A zero value
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implies that the platform supports unlimited floor performance levels.
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This file is only visible on platforms that support the CPPC
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Performance Priority feature.
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**Note**: When ``amd_pstate_floor_count`` is non-zero, the frequency to
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which the CPU is throttled under power or thermal constraints is
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undefined when the number of unique values of ``amd_pstate_floor_freq``
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across all CPUs in the system exceeds ``amd_pstate_floor_count``.
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``energy_performance_available_preferences``
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