diff options
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/cpu-freq/cpufreq-stats.rst (renamed from Documentation/cpu-freq/cpufreq-stats.txt) | 119 | ||||
-rw-r--r-- | Documentation/cpu-freq/index.rst | 1 |
2 files changed, 65 insertions, 55 deletions
diff --git a/Documentation/cpu-freq/cpufreq-stats.txt b/Documentation/cpu-freq/cpufreq-stats.rst index 14378cecb172..9ad695b1c7db 100644 --- a/Documentation/cpu-freq/cpufreq-stats.txt +++ b/Documentation/cpu-freq/cpufreq-stats.rst @@ -1,21 +1,23 @@ +.. SPDX-License-Identifier: GPL-2.0 - CPU frequency and voltage scaling statistics in the Linux(TM) kernel +========================================== +General Description of sysfs CPUFreq Stats +========================================== +information for users - L i n u x c p u f r e q - s t a t s d r i v e r - - information for users - +Author: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> +.. Contents - Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> - -Contents -1. Introduction -2. Statistics Provided (with example) -3. Configuring cpufreq-stats + 1. Introduction + 2. Statistics Provided (with example) + 3. Configuring cpufreq-stats 1. Introduction +=============== cpufreq-stats is a driver that provides CPU frequency statistics for each CPU. These statistics are provided in /sysfs as a bunch of read_only interfaces. This @@ -28,8 +30,10 @@ that may be running on your CPU. So, it will work with any cpufreq_driver. 2. Statistics Provided (with example) +===================================== cpufreq stats provides following statistics (explained in detail below). + - time_in_state - total_trans - trans_table @@ -39,53 +43,57 @@ All the statistics will be from the time the stats driver has been inserted statistic is done. Obviously, stats driver will not have any information about the frequency transitions before the stats driver insertion. --------------------------------------------------------------------------------- -<mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # ls -l -total 0 -drwxr-xr-x 2 root root 0 May 14 16:06 . -drwxr-xr-x 3 root root 0 May 14 15:58 .. ---w------- 1 root root 4096 May 14 16:06 reset --r--r--r-- 1 root root 4096 May 14 16:06 time_in_state --r--r--r-- 1 root root 4096 May 14 16:06 total_trans --r--r--r-- 1 root root 4096 May 14 16:06 trans_table --------------------------------------------------------------------------------- - -- reset +:: + + <mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # ls -l + total 0 + drwxr-xr-x 2 root root 0 May 14 16:06 . + drwxr-xr-x 3 root root 0 May 14 15:58 .. + --w------- 1 root root 4096 May 14 16:06 reset + -r--r--r-- 1 root root 4096 May 14 16:06 time_in_state + -r--r--r-- 1 root root 4096 May 14 16:06 total_trans + -r--r--r-- 1 root root 4096 May 14 16:06 trans_table + +- **reset** + Write-only attribute that can be used to reset the stat counters. This can be useful for evaluating system behaviour under different governors without the need for a reboot. -- time_in_state +- **time_in_state** + This gives the amount of time spent in each of the frequencies supported by this CPU. The cat output will have "<frequency> <time>" pair in each line, which will mean this CPU spent <time> usertime units of time at <frequency>. Output -will have one line for each of the supported frequencies. usertime units here +will have one line for each of the supported frequencies. usertime units here is 10mS (similar to other time exported in /proc). --------------------------------------------------------------------------------- -<mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # cat time_in_state -3600000 2089 -3400000 136 -3200000 34 -3000000 67 -2800000 172488 --------------------------------------------------------------------------------- +:: + <mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # cat time_in_state + 3600000 2089 + 3400000 136 + 3200000 34 + 3000000 67 + 2800000 172488 -- total_trans -This gives the total number of frequency transitions on this CPU. The cat + +- **total_trans** + +This gives the total number of frequency transitions on this CPU. The cat output will have a single count which is the total number of frequency transitions. --------------------------------------------------------------------------------- -<mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # cat total_trans -20 --------------------------------------------------------------------------------- +:: + + <mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # cat total_trans + 20 + +- **trans_table** -- trans_table This will give a fine grained information about all the CPU frequency transitions. The cat output here is a two dimensional matrix, where an entry -<i,j> (row i, column j) represents the count of number of transitions from +<i,j> (row i, column j) represents the count of number of transitions from Freq_i to Freq_j. Freq_i rows and Freq_j columns follow the sorting order in which the driver has provided the frequency table initially to the cpufreq core and so can be sorted (ascending or descending) or unsorted. The output here @@ -95,26 +103,27 @@ readability. If the transition table is bigger than PAGE_SIZE, reading this will return an -EFBIG error. --------------------------------------------------------------------------------- -<mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # cat trans_table - From : To - : 3600000 3400000 3200000 3000000 2800000 - 3600000: 0 5 0 0 0 - 3400000: 4 0 2 0 0 - 3200000: 0 1 0 2 0 - 3000000: 0 0 1 0 3 - 2800000: 0 0 0 2 0 --------------------------------------------------------------------------------- +:: + <mysystem>:/sys/devices/system/cpu/cpu0/cpufreq/stats # cat trans_table + From : To + : 3600000 3400000 3200000 3000000 2800000 + 3600000: 0 5 0 0 0 + 3400000: 4 0 2 0 0 + 3200000: 0 1 0 2 0 + 3000000: 0 0 1 0 3 + 2800000: 0 0 0 2 0 3. Configuring cpufreq-stats +============================ + +To configure cpufreq-stats in your kernel:: -To configure cpufreq-stats in your kernel -Config Main Menu - Power management options (ACPI, APM) ---> - CPU Frequency scaling ---> - [*] CPU Frequency scaling - [*] CPU frequency translation statistics + Config Main Menu + Power management options (ACPI, APM) ---> + CPU Frequency scaling ---> + [*] CPU Frequency scaling + [*] CPU frequency translation statistics "CPU Frequency scaling" (CONFIG_CPU_FREQ) should be enabled to configure diff --git a/Documentation/cpu-freq/index.rst b/Documentation/cpu-freq/index.rst index fcc58b2eee01..aba7831ab1cb 100644 --- a/Documentation/cpu-freq/index.rst +++ b/Documentation/cpu-freq/index.rst @@ -16,6 +16,7 @@ Author: Dominik Brodowski <linux@brodo.de> core cpu-drivers + cpufreq-stats Mailing List ------------ |