linux-hardened/Documentation/thermal
Viresh Kumar 8ea229511e thermal: Add cooling device's statistics in sysfs
This extends the sysfs interface for thermal cooling devices and exposes
some pretty useful statistics. These statistics have proven to be quite
useful specially while doing benchmarks related to the task scheduler,
where we want to make sure that nothing has disrupted the test,
specially the cooling device which may have put constraints on the CPUs.
The information exposed here tells us to what extent the CPUs were
constrained by the thermal framework.

The write-only "reset" file is used to reset the statistics.

The read-only "time_in_state_ms" file shows the time (in msec) spent by the
device in the respective cooling states, and it prints one line per
cooling state.

The read-only "total_trans" file shows single positive integer value
showing the total number of cooling state transitions the device has
gone through since the time the cooling device is registered or the time
when statistics were reset last.

The read-only "trans_table" file shows a two dimensional matrix, where
an entry <i,j> (row i, column j) represents the number of transitions
from State_i to State_j.

This is how the directory structure looks like for a single cooling
device:

$ ls -R /sys/class/thermal/cooling_device0/
/sys/class/thermal/cooling_device0/:
cur_state  max_state  power  stats  subsystem  type  uevent

/sys/class/thermal/cooling_device0/power:
autosuspend_delay_ms  runtime_active_time  runtime_suspended_time
control               runtime_status

/sys/class/thermal/cooling_device0/stats:
reset  time_in_state_ms  total_trans  trans_table

This is tested on ARM 64-bit Hisilicon hikey620 board running Ubuntu and
ARM 64-bit Hisilicon hikey960 board running Android.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
2018-04-02 21:49:01 +08:00
..
cpu-cooling-api.txt cpu_cooling: Remove static-power related documentation 2018-01-03 13:11:48 +01:00
exynos_thermal Documentation: thermal: Explain the exynos thermal driver model 2013-08-13 09:52:04 -04:00
exynos_thermal_emulation doc: fix misspellings with 'codespell' tool 2013-05-28 12:02:12 +02:00
intel_powerclamp.txt Doc/PM: Sync with intel_powerclamp code behavior 2017-04-20 15:35:03 -06:00
nouveau_thermal Documentation: fix spelling mistakes of "Celcius" -- > "Celsius" 2017-01-04 14:36:17 -07:00
power_allocator.txt thermal: power_allocator: relax the requirement of two passive trip points 2015-09-14 07:41:45 -07:00
sysfs-api.txt thermal: Add cooling device's statistics in sysfs 2018-04-02 21:49:01 +08:00
x86_pkg_temperature_thermal Thermal: Documentation for x86 package temperature thermal driver 2013-06-18 06:27:57 +08:00