[PATCH v14 4/5] Documentation: cpufreq: amd-pstate: update doc for Per CPU boost control method

Mario Limonciello
2024-06-24T21:34:24Z

From: Perry Yuan <perry.yuan@amd.com>

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 `boost`
sysfs attribute.

Signed-off-by: Perry Yuan <perry.yuan@amd.com>
Co-developed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
Documentation/admin-guide/pm/amd-pstate.rst | 16 ++++++++++++++++
1 file changed, 16 insertions(+)

diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst
index f5ee81419a93..d0324d44f548 100644
--- a/Documentation/admin-guide/pm/amd-pstate.rst
+++ b/Documentation/admin-guide/pm/amd-pstate.rst
@@ -281,6 +281,22 @@ 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.

+``boost``
+The `boost` 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 `boost` 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/boost`, where `X` represents the CPU number.
+
Other performance and frequency values can be read back from
``/sys/devices/system/cpu/cpuX/acpi_cppc/``, see :ref:`cppc_sysfs`.

--
2.43.0