[PATCH 1/4] cpufreq: intel_pstate: Documentation: Add references sections

From: Rafael J. Wysocki
Date: Wed Apr 03 2019 - 18:10:49 EST


From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

Add separate refereces sections to the cpufreq.rst and
intel_pstate.rst documents under admin-quide/pm and list the
references to external documentation in there.

Update the ACPI specification URL while at it.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
---
Documentation/admin-guide/pm/cpufreq.rst | 10 +++++++---
Documentation/admin-guide/pm/intel_pstate.rst | 25 ++++++++++++++++---------
2 files changed, 23 insertions(+), 12 deletions(-)

Index: linux-pm/Documentation/admin-guide/pm/intel_pstate.rst
===================================================================
--- linux-pm.orig/Documentation/admin-guide/pm/intel_pstate.rst
+++ linux-pm/Documentation/admin-guide/pm/intel_pstate.rst
@@ -20,11 +20,10 @@ you have not done that yet.]

For the processors supported by ``intel_pstate``, the P-state concept is broader
than just an operating frequency or an operating performance point (see the
-`LinuxCon Europe 2015 presentation by Kristen Accardi <LCEU2015_>`_ for more
+LinuxCon Europe 2015 presentation by Kristen Accardi [1]_ for more
information about that). For this reason, the representation of P-states used
by ``intel_pstate`` internally follows the hardware specification (for details
-refer to `Intel 64 and IA-32 Architectures Software Developerâs Manual
-Volume 3: System Programming Guide <SDM_>`_). However, the ``CPUFreq`` core
+refer to Intel Software Developerâs Manual [2]_). However, the ``CPUFreq`` core
uses frequencies for identifying operating performance points of CPUs and
frequencies are involved in the user space interface exposed by it, so
``intel_pstate`` maps its internal representation of P-states to frequencies too
@@ -561,9 +560,9 @@ or to pin every task potentially sensiti

On the majority of systems supported by ``intel_pstate``, the ACPI tables
provided by the platform firmware contain ``_PSS`` objects returning information
-that can be used for CPU performance scaling (refer to the `ACPI specification`_
-for details on the ``_PSS`` objects and the format of the information returned
-by them).
+that can be used for CPU performance scaling (refer to the ACPI specification
+[3]_ for details on the ``_PSS`` objects and the format of the information
+returned by them).

The information returned by the ACPI ``_PSS`` objects is used by the
``acpi-cpufreq`` scaling driver. On systems supported by ``intel_pstate``
@@ -728,6 +727,14 @@ P-state is called, the ``ftrace`` filter
<idle>-0 [000] ..s. 2537.654843: intel_pstate_set_pstate <-intel_pstate_timer_func


-.. _LCEU2015: http://events.linuxfoundation.org/sites/events/files/slides/LinuxConEurope_2015.pdf
-.. _SDM: http://www.intel.com/content/www/us/en/architecture-and-technology/64-ia-32-architectures-software-developer-system-programming-manual-325384.html
-.. _ACPI specification: http://www.uefi.org/sites/default/files/resources/ACPI_6_1.pdf
+References
+==========
+
+.. [1] Kristen Accardi, *Balancing Power and Performance in the Linux Kernel*,
+ http://events.linuxfoundation.org/sites/events/files/slides/LinuxConEurope_2015.pdf
+
+.. [2] *Intel 64 and IA-32 Architectures Software Developerâs Manual Volume 3: System Programming Guide*,
+ http://www.intel.com/content/www/us/en/architecture-and-technology/64-ia-32-architectures-software-developer-system-programming-manual-325384.html
+
+.. [3] *Advanced Configuration and Power Interface Specification*,
+ https://uefi.org/sites/default/files/resources/ACPI_6_3_final_Jan30.pdf
Index: linux-pm/Documentation/admin-guide/pm/cpufreq.rst
===================================================================
--- linux-pm.orig/Documentation/admin-guide/pm/cpufreq.rst
+++ linux-pm/Documentation/admin-guide/pm/cpufreq.rst
@@ -396,8 +396,8 @@ RT or deadline scheduling classes, the g
the allowed maximum (that is, the ``scaling_max_freq`` policy limit). In turn,
if it is invoked by the CFS scheduling class, the governor will use the
Per-Entity Load Tracking (PELT) metric for the root control group of the
-given CPU as the CPU utilization estimate (see the `Per-entity load tracking`_
-LWN.net article for a description of the PELT mechanism). Then, the new
+given CPU as the CPU utilization estimate (see the *Per-entity load tracking*
+LWN.net article [1]_ for a description of the PELT mechanism). Then, the new
CPU frequency to apply is computed in accordance with the formula

f = 1.25 * ``f_0`` * ``util`` / ``max``
@@ -698,4 +698,8 @@ hardware feature (e.g. all Intel ones),
:c:macro:`CONFIG_X86_ACPI_CPUFREQ_CPB` configuration option is set.


-.. _Per-entity load tracking: https://lwn.net/Articles/531853/
+References
+==========
+
+.. [1] Jonathan Corbet, *Per-entity load tracking*,
+ https://lwn.net/Articles/531853/