diff options
Diffstat (limited to 'Documentation/cpu-freq/cpufreq-stats.txt')
| -rw-r--r-- | Documentation/cpu-freq/cpufreq-stats.txt | 32 |
1 files changed, 13 insertions, 19 deletions
diff --git a/Documentation/cpu-freq/cpufreq-stats.txt b/Documentation/cpu-freq/cpufreq-stats.txt index fc647492e940..2bbe207354ed 100644 --- a/Documentation/cpu-freq/cpufreq-stats.txt +++ b/Documentation/cpu-freq/cpufreq-stats.txt @@ -34,21 +34,27 @@ cpufreq stats provides following statistics (explained in detail below). - 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. +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 @@ -103,26 +109,14 @@ 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 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 -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. +statistics which includes time_in_state, total_trans and trans_table. -Once these two options are enabled and your CPU supports cpufrequency, you +Once this option is enabled and your CPU supports cpufrequency, you will be able to see the CPU frequency statistics in /sysfs. - - - - |