[Patch 4/5] Documentation: ACPI: add autonomous mode ctrls info in cppc_sysfs.txt

Sumit Gupta
2025-02-11T10:38:31Z

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Add information about the CPC registers used during Autonomous
Performance Level Selection mode. Also, add information about other
regsiters like Guaranteed performance and Performance limited.

Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
---
Documentation/admin-guide/acpi/cppc_sysfs.rst | 28 +++++++++++++++++++
1 file changed, 28 insertions(+)

diff --git a/Documentation/admin-guide/acpi/cppc_sysfs.rst b/Documentation/admin-guide/acpi/cppc_sysfs.rst
index 36981c667823..ff3f48d95bb7 100644
--- a/Documentation/admin-guide/acpi/cppc_sysfs.rst
+++ b/Documentation/admin-guide/acpi/cppc_sysfs.rst
@@ -27,22 +27,33 @@ for each cpu X::
$ ls -lR /sys/devices/system/cpu/cpu0/acpi_cppc/
/sys/devices/system/cpu/cpu0/acpi_cppc/:
total 0
+ -r--r--r-- 1 root root 65536 Mar 5 19:38 auto_activity_window
+ -rw-r--r-- 1 root root 65536 Mar 5 19:38 auto_sel
+ -rw-r--r-- 1 root root 65536 Mar 5 19:38 energy_perf
-r--r--r-- 1 root root 65536 Mar 5 19:38 feedback_ctrs
+ -r--r--r-- 1 root root 65536 Mar 5 19:38 guaranteed_perf
-r--r--r-- 1 root root 65536 Mar 5 19:38 highest_perf
-r--r--r-- 1 root root 65536 Mar 5 19:38 lowest_freq
-r--r--r-- 1 root root 65536 Mar 5 19:38 lowest_nonlinear_perf
-r--r--r-- 1 root root 65536 Mar 5 19:38 lowest_perf
+ -rw-r--r-- 1 root root 65536 Mar 5 19:38 max_perf
+ -rw-r--r-- 1 root root 65536 Mar 5 19:38 min_perf
-r--r--r-- 1 root root 65536 Mar 5 19:38 nominal_freq
-r--r--r-- 1 root root 65536 Mar 5 19:38 nominal_perf
+ -r--r--r-- 1 root root 65536 Mar 5 19:38 per_limited
-r--r--r-- 1 root root 65536 Mar 5 19:38 reference_perf
-r--r--r-- 1 root root 65536 Mar 5 19:38 wraparound_time

+Performance Capabilities / Thresholds:
* highest_perf : Highest performance of this processor (abstract scale).
* nominal_perf : Highest sustained performance of this processor
(abstract scale).
* lowest_nonlinear_perf : Lowest performance of this processor with nonlinear
power savings (abstract scale).
* lowest_perf : Lowest performance of this processor (abstract scale).
+* guaranteed_perf : Current maximum sustained performance level of a processor,
+ taking into account all known external constraints. All processors are expected
+ to be able to sustain their guaranteed performance levels simultaneously.

* lowest_freq : CPU frequency corresponding to lowest_perf (in MHz).
* nominal_freq : CPU frequency corresponding to nominal_perf (in MHz).
@@ -50,6 +61,7 @@ for each cpu X::
frequency instead of abstract scale. These values should not be used for any
functional decisions.

+Performance Feedback:
* feedback_ctrs : Includes both Reference and delivered performance counter.
Reference counter ticks up proportional to processor's reference performance.
Delivered counter ticks up proportional to processor's delivered performance.
@@ -57,6 +69,22 @@ for each cpu X::
(seconds).
* reference_perf : Performance level at which reference performance counter
accumulates (abstract scale).
+* perf_limited : Set when Delivered Performance has been constrained due to an
+ unpredictable event. It is not utilized when Autonomous Selection is enabled.
+
+Performance Controls:
+* max_perf : Maximum performance level at which the platform may run in the
+ range [Lowest Performance, Highest Performance], inclusive.
+* min_perf : Minimum performance level at which the platform may run in the
+ range [Lowest Performance, Highest Performance], inclusive but must be set
+ to a value that is less than or equal to that specified by the max_perf.
+* auto_sel : Enable Autonomous Performance Level Selection on this processor.
+* auto_activity_window : Indicates a moving utilization sensitivity window to
+ the platform’s autonomous selection policy.
+* energy_perf: Provides a value ranging from 0 (performance preference) to
+ 0xFF (energy efficiency preference) that influences the rate of performance
+ increase /decrease and the result of the hardware's energy efficiency and
+ performance optimization policies.

Computing Average Delivered Performance
--
2.25.1