Hello Amit,
some comments embedded.
On Wed, Jan 18, 2012 at 02:51:07PM +0530, Amit Daniel Kachhap wrote:
> Add a sysfs node code to report effective cooling of all cooling devices
> attached to each trip points of a thermal zone. The cooling data reported
> will be absolute if the higher temperature trip points are arranged first
> otherwise the cooling stats is the cumulative effect of the earlier
> invoked cooling handlers.
>
> The basic assumption is that cooling devices will bring down the temperature
> in a symmetric manner and those statistics can be stored back and used for
> further tuning of the system.
>
> Signed-off-by: Amit Daniel Kachhap <amit.kach...@linaro.org>
> ---
> Documentation/thermal/sysfs-api.txt | 10 ++++
> drivers/thermal/thermal_sys.c | 96
> +++++++++++++++++++++++++++++++++++
> include/linux/thermal.h | 8 +++
> 3 files changed, 114 insertions(+), 0 deletions(-)
>
> diff --git a/Documentation/thermal/sysfs-api.txt
> b/Documentation/thermal/sysfs-api.txt
> index b61e46f..1db9a9d 100644
> --- a/Documentation/thermal/sysfs-api.txt
> +++ b/Documentation/thermal/sysfs-api.txt
> @@ -209,6 +209,13 @@ passive
> Valid values: 0 (disabled) or greater than 1000
> RW, Optional
>
> +trip_stats
> + This attribute presents the effective cooling generated from all the
> + cooling devices attached to a trip point. The output is a pair of value
> + for each trip point. Each pair represents
> + (trip index, cooling temperature difference in millidegree Celsius)
> + RO, Optional
> +
> *****************************
> * Cooling device attributes *
> *****************************
> @@ -261,6 +268,9 @@ method, the sys I/F structure will be built like this:
> |---cdev0_trip_point: 1 /* cdev0 can be used for passive */
> |---cdev1: --->/sys/class/thermal/cooling_device3
> |---cdev1_trip_point: 2 /* cdev1 can be used for active[0]*/
> + |---trip_stats 0 0
> + 1 8000 /*trip 1 causes 8 degree Celsius drop*/
> + 2 3000 /*trip 2 causes 3 degree Celsius drop*/
>
> |cooling_device0:
> |---type: Processor
> diff --git a/drivers/thermal/thermal_sys.c b/drivers/thermal/thermal_sys.c
> index dd9a574..47e7b6e 100644
> --- a/drivers/thermal/thermal_sys.c
> +++ b/drivers/thermal/thermal_sys.c
> @@ -92,6 +92,64 @@ static void release_idr(struct idr *idr, struct mutex
> *lock, int id)
> if (lock)
> mutex_unlock(lock);
> }
> +static void update_cooling_stats(struct thermal_zone_device *tz, long
> cur_temp)
> +{
> + int count, max_index, cur_interval;
> + long trip_temp, max_temp = 0, cool_temp;
> + static int last_trip_level = -1;
I got confused here. Are you sure using a static variable here is safe? I
suppose this function
is called for any thermal_zone_device, which in turns, may have different
amount of trips, and
different update rate. You may be using last_trip_level as reference for a
different tz. Meaning,
you would be screwing the stat buffers silently.
If that is the case, I suggest you to move this to your stat structure.
> +
> + if (cur_temp >= tz->last_temperature)
> + return;
> +
> + /* find the trip according to last temperature */
> + for (count = 0; count < tz->trips; count++) {
> + tz->ops->get_trip_temp(tz, count, &trip_temp);
> + if (tz->last_temperature >= trip_temp) {
> + if (max_temp < trip_temp) {
> + max_temp = trip_temp;
> + max_index = count;
> + }
> + }
> + }
> +
> + if (!max_temp) {
> + last_trip_level = -1;
> + return;
> + }
> +
> + cur_interval = tz->stat[max_index].interval_ptr;
> + cool_temp = tz->last_temperature - cur_temp;
> +
> + if (last_trip_level != max_index) {
> + if (++cur_interval == INTERVAL_HISTORY)
> + cur_interval = 0;
> + tz->stat[max_index].cool_temp[cur_interval] = cool_temp;
> + tz->stat[max_index].interval_ptr = cur_interval;
> + last_trip_level = max_index;
> + } else {
> + tz->stat[max_index].cool_temp[cur_interval] += cool_temp;
Why do you need to sum up here? Wouldn't this break your statistics? (I may
completely missed your idea for last_trip_level).
> + }
> +}
> +
> +static int calculate_cooling_temp_avg(struct thermal_zone_device *tz, int
> trip,
> + int *avg_cool)
> +{
> + int result = 0, count = 0, used_data = 0;
> +
> + if (trip > THERMAL_MAX_TRIPS)
Shouldn't this be checked against tz->trips ? At least you allocate your *stat
based on it.
> + return -EINVAL;
> +
> + *avg_cool = 0;
> + for (count = 0; count < INTERVAL_HISTORY; count++) {
> + if (tz->stat[trip].cool_temp[count] > 0) {
> + *avg_cool += tz->stat[trip].cool_temp[count];
> + used_data++;
> + }
> + }
> + if (used_data > 1)
> + *avg_cool = (*avg_cool)/used_data;
IIRC, the preferred operator style is (*avg_cool) / used_data
> + return result;
result is used only to hold a 0 here?
> +}
>
> /* sys I/F for thermal zone */
>
> @@ -493,6 +551,26 @@ temp_crit_show(struct device *dev, struct
> device_attribute *attr,
> return sprintf(buf, "%ld\n", temperature);
> }
>
> +static ssize_t
> +thermal_cooling_trip_stats_show(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + struct thermal_zone_device *tz = to_thermal_zone(dev);
> + int avg_cool = 0, result, trip_index;
> + ssize_t len = 0;
> +
> + for (trip_index = 0; trip_index < tz->trips; trip_index++) {
> + result = calculate_cooling_temp_avg(tz,
> + trip_index, &avg_cool);
> + if (!result)
> + len += sprintf(buf + len, "%d %d\n",
> + trip_index, avg_cool);
> + }
> + return len;
> +}
> +static DEVICE_ATTR(trip_stats, 0444,
> + thermal_cooling_trip_stats_show, NULL);
>
> static struct thermal_hwmon_device *
> thermal_hwmon_lookup_by_type(const struct thermal_zone_device *tz)
> @@ -1049,6 +1127,8 @@ void thermal_zone_device_update(struct
> thermal_zone_device *tz)
> goto leave;
> }
>
> + update_cooling_stats(tz, temp);
> +
> for (count = 0; count < tz->trips; count++) {
> tz->ops->get_trip_type(tz, count, &trip_type);
> tz->ops->get_trip_temp(tz, count, &trip_temp);
> @@ -1181,6 +1261,13 @@ struct thermal_zone_device
> *thermal_zone_device_register(char *type,
> return ERR_PTR(result);
> }
>
> + /*Allocate variables for cooling stats*/
> + tz->stat = devm_kzalloc(&tz->device,
> + sizeof(struct thermal_cooling_stats) * trips,
> + GFP_KERNEL);
You never free this memory here.
> + if (!tz->stat)
> + goto unregister;
> +
> /* sys I/F */
> if (type) {
> result = device_create_file(&tz->device, &dev_attr_type);
> @@ -1207,6 +1294,12 @@ struct thermal_zone_device
> *thermal_zone_device_register(char *type,
> passive = 1;
> }
>
> + if (trips > 0) {
> + result = device_create_file(&tz->device, &dev_attr_trip_stats);
> + if (result)
> + goto unregister;
The failing paths after your allocation point must consider freeing the memory
you requested.
> + }
> +
> if (!passive)
> result = device_create_file(&tz->device,
> &dev_attr_passive);
> @@ -1282,6 +1375,9 @@ void thermal_zone_device_unregister(struct
> thermal_zone_device *tz)
> for (count = 0; count < tz->trips; count++)
> TRIP_POINT_ATTR_REMOVE(&tz->device, count);
>
> + if (tz->trips > 0)
> + device_remove_file(&tz->device, &dev_attr_trip_stats);
> +
Amit,
I think here it would be a good place to free the memory you allocated for *stat
> thermal_remove_hwmon_sysfs(tz);
> release_idr(&thermal_tz_idr, &thermal_idr_lock, tz->id);
> idr_destroy(&tz->idr);
> diff --git a/include/linux/thermal.h b/include/linux/thermal.h
> index 47b4a27..47504c7 100644
> --- a/include/linux/thermal.h
> +++ b/include/linux/thermal.h
> @@ -72,6 +72,13 @@ struct thermal_cooling_device_ops {
> #define THERMAL_TRIPS_NONE -1
> #define THERMAL_MAX_TRIPS 12
> #define THERMAL_NAME_LENGTH 20
> +#define INTERVAL_HISTORY 12
> +
> +struct thermal_cooling_stats {
> + int cool_temp[INTERVAL_HISTORY];
> + int interval_ptr;
> +};
> +
> struct thermal_cooling_device {
> int id;
> char type[THERMAL_NAME_LENGTH];
> @@ -102,6 +109,7 @@ struct thermal_zone_device {
> struct list_head cooling_devices;
> struct idr idr;
> struct mutex lock; /* protect cooling devices list */
> + struct thermal_cooling_stats *stat;
> struct list_head node;
> struct delayed_work poll_queue;
> };
> --
> 1.7.1
>
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