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Message-Id: <20190423162932.21428-22-changbin.du@gmail.com>
Date: Wed, 24 Apr 2019 00:28:50 +0800
From: Changbin Du <changbin.du@...il.com>
To: Jonathan Corbet <corbet@....net>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>, rjw@...ysocki.net,
linux-pci@...r.kernel.org, linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com,
x86@...nel.org, fenghua.yu@...el.com,
linuxppc-dev@...ts.ozlabs.org, linux-acpi@...r.kernel.org,
linux-gpio@...r.kernel.org, mchehab+samsung@...nel.org,
Changbin Du <changbin.du@...il.com>
Subject: [PATCH v4 21/63] Documentation: ACPI: move cppc_sysfs.txt to admin-guide/acpi and convert to reST
This converts the plain text documentation to reStructuredText format and
add it to Sphinx TOC tree. No essential content change.
Signed-off-by: Changbin Du <changbin.du@...il.com>
---
.../acpi/cppc_sysfs.rst} | 71 ++++++++++---------
Documentation/admin-guide/acpi/index.rst | 1 +
2 files changed, 40 insertions(+), 32 deletions(-)
rename Documentation/{acpi/cppc_sysfs.txt => admin-guide/acpi/cppc_sysfs.rst} (51%)
diff --git a/Documentation/acpi/cppc_sysfs.txt b/Documentation/admin-guide/acpi/cppc_sysfs.rst
similarity index 51%
rename from Documentation/acpi/cppc_sysfs.txt
rename to Documentation/admin-guide/acpi/cppc_sysfs.rst
index f20fb445135d..a4b99afbe331 100644
--- a/Documentation/acpi/cppc_sysfs.txt
+++ b/Documentation/admin-guide/acpi/cppc_sysfs.rst
@@ -1,5 +1,11 @@
+.. SPDX-License-Identifier: GPL-2.0
- Collaborative Processor Performance Control (CPPC)
+==================================================
+Collaborative Processor Performance Control (CPPC)
+==================================================
+
+CPPC
+====
CPPC defined in the ACPI spec describes a mechanism for the OS to manage the
performance of a logical processor on a contigious and abstract performance
@@ -10,31 +16,28 @@ For more details on CPPC please refer to the ACPI specification at:
http://uefi.org/specifications
-Some of the CPPC registers are exposed via sysfs under:
-
-/sys/devices/system/cpu/cpuX/acpi_cppc/
-
-for each cpu X
+Some of the CPPC registers are exposed via sysfs under::
---------------------------------------------------------------------------------
+ /sys/devices/system/cpu/cpuX/acpi_cppc/
-$ 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 feedback_ctrs
--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
--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 reference_perf
--r--r--r-- 1 root root 65536 Mar 5 19:38 wraparound_time
+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 feedback_ctrs
+ -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
+ -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 reference_perf
+ -r--r--r-- 1 root root 65536 Mar 5 19:38 wraparound_time
* highest_perf : Highest performance of this processor (abstract scale).
-* nominal_perf : Highest sustained 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).
@@ -48,22 +51,26 @@ total 0
* 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.
-* wraparound_time: Minimum time for the feedback counters to wraparound (seconds).
+* wraparound_time: Minimum time for the feedback counters to wraparound
+ (seconds).
* reference_perf : Performance level at which reference performance counter
accumulates (abstract scale).
---------------------------------------------------------------------------------
- Computing Average Delivered Performance
+Computing Average Delivered Performance
+=======================================
+
+Below describes the steps to compute the average performance delivered by
+taking two different snapshots of feedback counters at time T1 and T2.
+
+ T1: Read feedback_ctrs as fbc_t1
+ Wait or run some workload
-Below describes the steps to compute the average performance delivered by taking
-two different snapshots of feedback counters at time T1 and T2.
+ T2: Read feedback_ctrs as fbc_t2
-T1: Read feedback_ctrs as fbc_t1
- Wait or run some workload
-T2: Read feedback_ctrs as fbc_t2
+::
-delivered_counter_delta = fbc_t2[del] - fbc_t1[del]
-reference_counter_delta = fbc_t2[ref] - fbc_t1[ref]
+ delivered_counter_delta = fbc_t2[del] - fbc_t1[del]
+ reference_counter_delta = fbc_t2[ref] - fbc_t1[ref]
-delivered_perf = (refernce_perf x delivered_counter_delta) / reference_counter_delta
+ delivered_perf = (refernce_perf x delivered_counter_delta) / reference_counter_delta
diff --git a/Documentation/admin-guide/acpi/index.rst b/Documentation/admin-guide/acpi/index.rst
index d68e9914c5ff..9049a7b9f065 100644
--- a/Documentation/admin-guide/acpi/index.rst
+++ b/Documentation/admin-guide/acpi/index.rst
@@ -10,3 +10,4 @@ the Linux ACPI support.
initrd_table_override
dsdt-override
+ cppc_sysfs
--
2.20.1
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