Documentation: intel_pstate: Describe hwp_dynamic_boost sysfs knob

[linux.git] / Documentation / admin-guide / pm / intel_pstate.rst

diff --git a/Documentation/admin-guide/pm/intel_pstate.rst b/Documentation/admin-guide/pm/intel_pstate.rst
index ab2fe0eda1d7c317faefab52363ce96755ac64d5..8f1d3de449b53fedcc78d1aee506e6882f2be90c 100644 (file)
--- a/Documentation/admin-guide/pm/intel_pstate.rst
+++ b/Documentation/admin-guide/pm/intel_pstate.rst
@@ -324,8 +324,7 @@ Global Attributes
 
 ``intel_pstate`` exposes several global attributes (files) in ``sysfs`` to
 control its functionality at the system level.  They are located in the
-``/sys/devices/system/cpu/cpufreq/intel_pstate/`` directory and affect all
-CPUs.
+``/sys/devices/system/cpu/intel_pstate/`` directory and affect all CPUs.
 
 Some of them are not present if the ``intel_pstate=per_cpu_perf_limits``
 argument is passed to the kernel in the command line.
@@ -379,6 +378,17 @@ argument is passed to the kernel in the command line.
        but it affects the maximum possible value of per-policy P-state limits
        (see `Interpretation of Policy Attributes`_ below for details).
 
+``hwp_dynamic_boost``
+       This attribute is only present if ``intel_pstate`` works in the
+       `active mode with the HWP feature enabled <Active Mode With HWP_>`_ in
+       the processor.  If set (equal to 1), it causes the minimum P-state limit
+       to be increased dynamically for a short time whenever a task previously
+       waiting on I/O is selected to run on a given logical CPU (the purpose
+       of this mechanism is to improve performance).
+
+       This setting has no effect on logical CPUs whose minimum P-state limit
+       is directly set to the highest non-turbo P-state or above it.
+
 .. _status_attr:
 
 ``status``
@@ -410,7 +420,7 @@ argument is passed to the kernel in the command line.
        That only is supported in some configurations, though (for example, if
        the `HWP feature is enabled in the processor <Active Mode With HWP_>`_,
        the operation mode of the driver cannot be changed), and if it is not
-       supported in the current configuration, writes to this attribute with
+       supported in the current configuration, writes to this attribute will
        fail with an appropriate error.
 
 Interpretation of Policy Attributes