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Diffstat (limited to 'Documentation/admin-guide/pm/intel_pstate.rst')
| -rw-r--r-- | Documentation/admin-guide/pm/intel_pstate.rst | 32 |
1 files changed, 21 insertions, 11 deletions
diff --git a/Documentation/admin-guide/pm/intel_pstate.rst b/Documentation/admin-guide/pm/intel_pstate.rst index ec0f7c111f65..67e414e34f37 100644 --- a/Documentation/admin-guide/pm/intel_pstate.rst +++ b/Documentation/admin-guide/pm/intel_pstate.rst @@ -1,10 +1,13 @@ +.. SPDX-License-Identifier: GPL-2.0 +.. include:: <isonum.txt> + =============================================== ``intel_pstate`` CPU Performance Scaling Driver =============================================== -:: +:Copyright: |copy| 2017 Intel Corporation - Copyright (c) 2017 Intel Corp., Rafael J. Wysocki <rafael.j.wysocki@intel.com> +:Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com> General Information @@ -20,11 +23,10 @@ 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 Developer’s Manual -Volume 3: System Programming Guide <SDM_>`_). However, the ``CPUFreq`` core +refer to Intel Software Developer’s 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 +563,9 @@ or to pin every task potentially sensitive to them to a specific CPU.] 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 +730,14 @@ P-state is called, the ``ftrace`` filter can be set to to <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 Developer’s 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 |