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[v9,7/7] Documentation: cpufreq: amd-pstate: update doc for Per CPU boost control method

Message ID 490ec11390350aa5814aa86a4e08cdefb7ce2832.1714989803.git.perry.yuan@amd.com
State Superseded
Headers show
Series AMD Pstate Driver Core Performance Boost | expand

Commit Message

Yuan, Perry May 6, 2024, 10:19 a.m. UTC
Updates the documentation in `amd-pstate.rst` to include information about the
per CPU boost control feature. Users can now enable or disable the Core Performance
Boost (CPB) feature on individual CPUs using the `amd_pstate_boost_cpb`
sysfs attribute.

Signed-off-by: Perry Yuan <perry.yuan@amd.com>
---
 Documentation/admin-guide/pm/amd-pstate.rst | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)
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Patch

diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst
index bcc0d9404c18..8c48b00fc8a3 100644
--- a/Documentation/admin-guide/pm/amd-pstate.rst
+++ b/Documentation/admin-guide/pm/amd-pstate.rst
@@ -281,6 +281,27 @@  integer values defined between 0 to 255 when EPP feature is enabled by platform
 firmware, if EPP feature is disabled, driver will ignore the written value
 This attribute is read-write.
 
+``amd_pstate_boost_cpb``
+The `amd_pstate_boost_cpb` sysfs attribute provides control over the CPU core
+performance boost, allowing users to manage the maximum frequency limitation
+of the CPU. This attribute can be used to enable or disable the boost feature
+on individual CPUs.
+
+When the boost feature is enabled, the CPU can dynamically increase its frequency
+beyond the base frequency, providing enhanced performance for demanding workloads.
+On the other hand, disabling the boost feature restricts the CPU to operate at the
+base frequency, which may be desirable in certain scenarios to prioritize power
+efficiency or manage temperature.
+
+To manipulate the `amd_pstate_boost_cpb` attribute, users can write a value of `0`
+to disable the boost or `1` to enable it, for the respective CPU using the sysfs path
+`/sys/devices/system/cpu/cpuX/cpufreq/amd_pstate_boost_cpb`, where `X` represents the
+CPU number.
+
+It is important to note that modifying the global variable
+`amd_pstate_global_params.cpb_boost` will override the individual CPU settings.
+
+
 Other performance and frequency values can be read back from
 ``/sys/devices/system/cpu/cpuX/acpi_cppc/``, see :ref:`cppc_sysfs`.