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Commit 8ea22951 authored by Viresh Kumar's avatar Viresh Kumar Committed by Zhang Rui
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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: default avatarViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: default avatarZhang Rui <rui.zhang@intel.com>
parent 0c8efd61

Documentation/thermal/sysfs-api.txt

+31 −0
Original line number Diff line number Diff line
@@ -255,6 +255,7 @@ temperature) and throttle appropriate devices. 
2. sysfs attributes structure



RO	read only value

WO	write only value

RW	read/write value



Thermal sysfs attributes will be represented under /sys/class/thermal.
@@ -286,6 +287,11 @@ Thermal cooling device sys I/F, created once it's registered: 
    |---type:			Type of the cooling device(processor/fan/...)

    |---max_state:		Maximum cooling state of the cooling device

    |---cur_state:		Current cooling state of the cooling device

    |---stats:			Directory containing cooling device's statistics

    |---stats/reset:		Writing any value resets the statistics

    |---stats/time_in_state_ms:	Time (msec) spent in various cooling states

    |---stats/total_trans:	Total number of times cooling state is changed

    |---stats/trans_table:	Cooing state transition table





Then next two dynamic attributes are created/removed in pairs. They represent
@@ -490,6 +496,31 @@ cur_state 
	- cur_state == max_state means the maximum cooling.

	RW, Required



stats/reset

	Writing any value resets the cooling device's statistics.

	WO, Required



stats/time_in_state_ms:

	The amount of time spent by the cooling device in various cooling

	states. The output will have "<state> <time>" pair in each line, which

	will mean this cooling device spent <time> msec of time at <state>.

	Output will have one line for each of the supported states.  usertime

	units here is 10mS (similar to other time exported in /proc).

	RO, Required



stats/total_trans:

	A single positive value showing the total number of times the state of a

	cooling device is changed.

	RO, Required



stats/trans_table:

	This gives fine grained information about all the cooling state

	transitions. The cat output here is a two dimensional matrix, where an

	entry <i,j> (row i, column j) represents the number of transitions from

	State_i to State_j. If the transition table is bigger than PAGE_SIZE,

	reading this will return an -EFBIG error.

	RO, Required



3. A simple implementation



ACPI thermal zone may support multiple trip points like critical, hot,

drivers/thermal/Kconfig

+7 −0
Original line number Diff line number Diff line
@@ -15,6 +15,13 @@ menuconfig THERMAL 


if THERMAL



config THERMAL_STATISTICS

	bool "Thermal state transition statistics"

	help

	  Export thermal state transition statistics information through sysfs.



	  If in doubt, say N.



config THERMAL_EMERGENCY_POWEROFF_DELAY_MS

	int "Emergency poweroff delay in milli-seconds"

	depends on THERMAL

drivers/thermal/thermal_core.c

+2 −1
Original line number Diff line number Diff line
@@ -972,8 +972,8 @@ __thermal_cooling_device_register(struct device_node *np, 
	cdev->ops = ops;

	cdev->updated = false;

	cdev->device.class = &thermal_class;

	thermal_cooling_device_setup_sysfs(cdev);

	cdev->devdata = devdata;

	thermal_cooling_device_setup_sysfs(cdev);

	dev_set_name(&cdev->device, "cooling_device%d", cdev->id);

	result = device_register(&cdev->device);

	if (result) {
@@ -1106,6 +1106,7 @@ void thermal_cooling_device_unregister(struct thermal_cooling_device *cdev) 


	ida_simple_remove(&thermal_cdev_ida, cdev->id);

	device_unregister(&cdev->device);

	thermal_cooling_device_destroy_sysfs(cdev);

}

EXPORT_SYMBOL_GPL(thermal_cooling_device_unregister);

drivers/thermal/thermal_core.h

+10 −0
Original line number Diff line number Diff line
@@ -73,6 +73,7 @@ int thermal_build_list_of_policies(char *buf); 
int thermal_zone_create_device_groups(struct thermal_zone_device *, int);

void thermal_zone_destroy_device_groups(struct thermal_zone_device *);

void thermal_cooling_device_setup_sysfs(struct thermal_cooling_device *);

void thermal_cooling_device_destroy_sysfs(struct thermal_cooling_device *cdev);

/* used only at binding time */

ssize_t

thermal_cooling_device_trip_point_show(struct device *,
@@ -84,6 +85,15 @@ ssize_t thermal_cooling_device_weight_store(struct device *, 
					    struct device_attribute *,

					    const char *, size_t);



#ifdef CONFIG_THERMAL_STATISTICS

void thermal_cooling_device_stats_update(struct thermal_cooling_device *cdev,

					 unsigned long new_state);

#else

static inline void

thermal_cooling_device_stats_update(struct thermal_cooling_device *cdev,

				    unsigned long new_state) {}

#endif /* CONFIG_THERMAL_STATISTICS */



#ifdef CONFIG_THERMAL_GOV_STEP_WISE

int thermal_gov_step_wise_register(void);

void thermal_gov_step_wise_unregister(void);

drivers/thermal/thermal_helpers.c

+4 −1
Original line number Diff line number Diff line
@@ -187,7 +187,10 @@ void thermal_cdev_update(struct thermal_cooling_device *cdev) 
		if (instance->target > target)

			target = instance->target;

	}

	cdev->ops->set_cur_state(cdev, target);



	if (!cdev->ops->set_cur_state(cdev, target))

		thermal_cooling_device_stats_update(cdev, target);



	cdev->updated = true;

	mutex_unlock(&cdev->lock);

	trace_cdev_update(cdev, target);