From mboxrd@z Thu Jan 1 00:00:00 1970 From: Changbin Du Subject: [PATCH v2 21/24] acpi doc: convert acpi/cppc_sysfs.txt to rst format Date: Fri, 29 Mar 2019 08:11:32 +0800 Message-ID: <20190329001135.15847-22-changbin.du@gmail.com> References: <20190329001135.15847-1-changbin.du@gmail.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20190329001135.15847-1-changbin.du@gmail.com> Sender: linux-kernel-owner@vger.kernel.org To: Jonathan Corbet Cc: rjw@rjwysocki.net, lenb@kernel.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, Changbin Du List-Id: linux-acpi@vger.kernel.org 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 --- .../acpi/{cppc_sysfs.txt => cppc_sysfs.rst} | 71 ++++++++++--------- Documentation/acpi/index.rst | 1 + 2 files changed, 40 insertions(+), 32 deletions(-) rename Documentation/acpi/{cppc_sysfs.txt => cppc_sysfs.rst} (51%) diff --git a/Documentation/acpi/cppc_sysfs.txt b/Documentation/acpi/cppc_sysfs.rst similarity index 51% rename from Documentation/acpi/cppc_sysfs.txt rename to Documentation/acpi/cppc_sysfs.rst index f20fb445135d..a4b99afbe331 100644 --- a/Documentation/acpi/cppc_sysfs.txt +++ b/Documentation/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/acpi/index.rst b/Documentation/acpi/index.rst index bdd82615fef6..91aeed814ea9 100644 --- a/Documentation/acpi/index.rst +++ b/Documentation/acpi/index.rst @@ -26,3 +26,4 @@ Linux ACPI (Advanced Configuration and Power Interface) aml-debugger apei/output_format apei/einj + cppc_sysfs -- 2.20.1