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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> |
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| .. | ||
| cpu-cooling-api.txt | ||
| exynos_thermal | ||
| exynos_thermal_emulation | ||
| intel_powerclamp.txt | ||
| nouveau_thermal | ||
| power_allocator.txt | ||
| sysfs-api.txt | ||
| x86_pkg_temperature_thermal | ||