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Diffstat (limited to 'Documentation/cpu-freq/cpufreq-stats.txt')
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diff --git a/Documentation/cpu-freq/cpufreq-stats.txt b/Documentation/cpu-freq/cpufreq-stats.txt deleted file mode 100644 index 14378cecb172..000000000000 --- a/Documentation/cpu-freq/cpufreq-stats.txt +++ /dev/null @@ -1,127 +0,0 @@ - - CPU frequency and voltage scaling statistics in the Linux(TM) kernel - - - 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 - - - - Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> - -Contents -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 -interface (when configured) will appear in a separate directory under cpufreq -in /sysfs (<sysfs root>/devices/system/cpu/cpuX/cpufreq/stats/) for each CPU. -Various statistics will form read_only files under this directory. - -This driver is designed to be independent of any particular cpufreq_driver -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 - -All the statistics will be from the time the stats driver has been inserted -(or the time the stats were reset) to the time when a read of a particular -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 -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 -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 -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 --------------------------------------------------------------------------------- - - -- 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 --------------------------------------------------------------------------------- - -- 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 -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 -also contains the actual freq values for each row and column for better -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 --------------------------------------------------------------------------------- - - -3. Configuring cpufreq-stats - -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 - - -"CPU Frequency scaling" (CONFIG_CPU_FREQ) should be enabled to configure -cpufreq-stats. - -"CPU frequency translation statistics" (CONFIG_CPU_FREQ_STAT) provides the -statistics which includes time_in_state, total_trans and trans_table. - -Once this option is enabled and your CPU supports cpufrequency, you -will be able to see the CPU frequency statistics in /sysfs. |