linux-kernel - [PATCH v10 7/7] Documentation: cpufreq: amd-pstate: update doc for Per CPU boost control method

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Date: Wed, 8 May 2024 15:21:12 +0800
From: Perry Yuan <perry.yuan@....com>
To: <rafael.j.wysocki@...el.com>, <Mario.Limonciello@....com>,
	<viresh.kumar@...aro.org>, <Ray.Huang@....com>, <gautham.shenoy@....com>,
	<Borislav.Petkov@....com>
CC: <Alexander.Deucher@....com>, <Xinmei.Huang@....com>,
	<Xiaojian.Du@....com>, <Li.Meng@....com>, <linux-pm@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: [PATCH v10 7/7] Documentation: cpufreq: amd-pstate: update doc for Per CPU boost control method

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@....com>
---
 Documentation/admin-guide/pm/amd-pstate.rst | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst
index bcc0d9404c18..98e43c53c387 100644
--- a/Documentation/admin-guide/pm/amd-pstate.rst
+++ b/Documentation/admin-guide/pm/amd-pstate.rst
@@ -281,6 +281,26 @@ 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.
+
+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`.
 
-- 
2.34.1