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[v13,9/9] Documentation: cpufreq: amd-pstate: update doc for Per CPU boost control method

Message ID d6298998073125cab0f822507aaac1300faec6a2.1718988436.git.perry.yuan@amd.com (mailing list archive)
State Superseded, archived
Delegated to: Mario Limonciello
Headers show
Series AMD Pstate Driver Core Performance Boost | expand

Commit Message

Yuan, Perry June 21, 2024, 4:51 p.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 `boost` sysfs attribute.

Signed-off-by: Perry Yuan <perry.yuan@amd.com>
Reviewed-by: Mario Limonciello <mario.limonciello@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 dc1b10d7dd09..57995f54f0c8 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.
 
+``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
+`/sys/devices/system/cpu/amd_pstate/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`.