summaryrefslogtreecommitdiffstats
path: root/Documentation/cpu-freq/cpufreq-stats.txt
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/cpu-freq/cpufreq-stats.txt')
-rw-r--r--Documentation/cpu-freq/cpufreq-stats.txt128
1 files changed, 0 insertions, 128 deletions
diff --git a/Documentation/cpu-freq/cpufreq-stats.txt b/Documentation/cpu-freq/cpufreq-stats.txt
deleted file mode 100644
index fc64749..0000000
--- a/Documentation/cpu-freq/cpufreq-stats.txt
+++ /dev/null
@@ -1,128 +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
-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 ..
--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
---------------------------------------------------------------------------------
-
-- 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 is in descending order with increasing rows and
-Freq_j is in descending order with increasing columns. The output here also
-contains the actual freq values for each row and column for better readability.
-
---------------------------------------------------------------------------------
-<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 translation statistics details
-
-
-"CPU Frequency scaling" (CONFIG_CPU_FREQ) should be enabled to configure
-cpufreq-stats.
-
-"CPU frequency translation statistics" (CONFIG_CPU_FREQ_STAT) provides the
-basic statistics which includes time_in_state and total_trans.
-
-"CPU frequency translation statistics details" (CONFIG_CPU_FREQ_STAT_DETAILS)
-provides fine grained cpufreq stats by trans_table. The reason for having a
-separate config option for trans_table is:
-- trans_table goes against the traditional /sysfs rule of one value per
- interface. It provides a whole bunch of value in a 2 dimensional matrix
- form.
-
-Once these two options are enabled and your CPU supports cpufrequency, you
-will be able to see the CPU frequency statistics in /sysfs.
-
-
-
-