docs: cpu-freq: convert cpufreq-stats.txt to ReST
- Add a SPDX header; - Add a document title, based on the original contents of cpu-freq/index.txt; - Use lists where needed; - Comment out the existing text-only index; - Adjust some title marks; - Use bold on some places; - Mark literal blocks as such; - Some whitespace fixes and new line breaks; - Add it to cpu-freq/index.rst. Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Mauro Carvalho Chehab
Rafael J. Wysocki
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8f92058987
commit
aadfa206e9
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@ -1,21 +1,23 @@
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.. SPDX-License-Identifier: GPL-2.0
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CPU frequency and voltage scaling statistics in the Linux(TM) kernel
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==========================================
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General Description of sysfs CPUFreq Stats
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==========================================
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information for users
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L i n u x c p u f r e q - s t a t s d r i v e r
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Author: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
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- information for users -
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.. Contents
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Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
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Contents
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1. Introduction
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2. Statistics Provided (with example)
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3. Configuring cpufreq-stats
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1. Introduction
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2. Statistics Provided (with example)
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3. Configuring cpufreq-stats
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1. Introduction
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===============
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cpufreq-stats is a driver that provides CPU frequency statistics for each CPU.
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These statistics are provided in /sysfs as a bunch of read_only interfaces. This
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@ -28,8 +30,10 @@ that may be running on your CPU. So, it will work with any cpufreq_driver.
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2. Statistics Provided (with example)
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=====================================
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cpufreq stats provides following statistics (explained in detail below).
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- time_in_state
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- total_trans
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- trans_table
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@ -39,53 +43,57 @@ All the statistics will be from the time the stats driver has been inserted
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statistic is done. Obviously, stats driver will not have any information
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about the frequency transitions before the stats driver insertion.
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--------------------------------------------------------------------------------
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<mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # ls -l
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total 0
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drwxr-xr-x 2 root root 0 May 14 16:06 .
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drwxr-xr-x 3 root root 0 May 14 15:58 ..
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--w------- 1 root root 4096 May 14 16:06 reset
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-r--r--r-- 1 root root 4096 May 14 16:06 time_in_state
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-r--r--r-- 1 root root 4096 May 14 16:06 total_trans
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-r--r--r-- 1 root root 4096 May 14 16:06 trans_table
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--------------------------------------------------------------------------------
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::
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<mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # ls -l
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total 0
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drwxr-xr-x 2 root root 0 May 14 16:06 .
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drwxr-xr-x 3 root root 0 May 14 15:58 ..
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--w------- 1 root root 4096 May 14 16:06 reset
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-r--r--r-- 1 root root 4096 May 14 16:06 time_in_state
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-r--r--r-- 1 root root 4096 May 14 16:06 total_trans
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-r--r--r-- 1 root root 4096 May 14 16:06 trans_table
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- **reset**
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- reset
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Write-only attribute that can be used to reset the stat counters. This can be
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useful for evaluating system behaviour under different governors without the
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need for a reboot.
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- time_in_state
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- **time_in_state**
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This gives the amount of time spent in each of the frequencies supported by
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this CPU. The cat output will have "<frequency> <time>" pair in each line, which
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will mean this CPU spent <time> usertime units of time at <frequency>. Output
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will have one line for each of the supported frequencies. usertime units here
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will have one line for each of the supported frequencies. usertime units here
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is 10mS (similar to other time exported in /proc).
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--------------------------------------------------------------------------------
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<mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # cat time_in_state
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3600000 2089
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3400000 136
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3200000 34
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3000000 67
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2800000 172488
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--------------------------------------------------------------------------------
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::
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<mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # cat time_in_state
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3600000 2089
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3400000 136
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3200000 34
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3000000 67
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2800000 172488
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- total_trans
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This gives the total number of frequency transitions on this CPU. The cat
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- **total_trans**
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This gives the total number of frequency transitions on this CPU. The cat
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output will have a single count which is the total number of frequency
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transitions.
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--------------------------------------------------------------------------------
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<mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # cat total_trans
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20
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--------------------------------------------------------------------------------
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::
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<mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # cat total_trans
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20
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- **trans_table**
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- trans_table
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This will give a fine grained information about all the CPU frequency
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transitions. The cat output here is a two dimensional matrix, where an entry
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<i,j> (row i, column j) represents the count of number of transitions from
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<i,j> (row i, column j) represents the count of number of transitions from
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Freq_i to Freq_j. Freq_i rows and Freq_j columns follow the sorting order in
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which the driver has provided the frequency table initially to the cpufreq core
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and so can be sorted (ascending or descending) or unsorted. The output here
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@ -95,26 +103,27 @@ readability.
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If the transition table is bigger than PAGE_SIZE, reading this will
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return an -EFBIG error.
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--------------------------------------------------------------------------------
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<mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # cat trans_table
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From : To
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: 3600000 3400000 3200000 3000000 2800000
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3600000: 0 5 0 0 0
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3400000: 4 0 2 0 0
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3200000: 0 1 0 2 0
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3000000: 0 0 1 0 3
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2800000: 0 0 0 2 0
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--------------------------------------------------------------------------------
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::
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<mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # cat trans_table
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From : To
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: 3600000 3400000 3200000 3000000 2800000
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3600000: 0 5 0 0 0
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3400000: 4 0 2 0 0
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3200000: 0 1 0 2 0
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3000000: 0 0 1 0 3
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2800000: 0 0 0 2 0
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3. Configuring cpufreq-stats
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============================
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To configure cpufreq-stats in your kernel
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Config Main Menu
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Power management options (ACPI, APM) --->
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CPU Frequency scaling --->
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[*] CPU Frequency scaling
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[*] CPU frequency translation statistics
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To configure cpufreq-stats in your kernel::
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Config Main Menu
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Power management options (ACPI, APM) --->
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CPU Frequency scaling --->
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[*] CPU Frequency scaling
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[*] CPU frequency translation statistics
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"CPU Frequency scaling" (CONFIG_CPU_FREQ) should be enabled to configure
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@ -16,6 +16,7 @@ Author: Dominik Brodowski <linux@brodo.de>
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core
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cpu-drivers
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cpufreq-stats
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Mailing List
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------------
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