Re: [PATCH 4/7] thermal: stats: introduce thermal zone stats/min_gradient

Rafael J. Wysocki
2023-06-20T17:17:31Z

On Fri, May 19, 2023 at 5:27 AM Eduardo Valentin <evalenti@kernel.org> wrote:
>
> From: Eduardo Valentin <eduval@amazon.com>
>
> The patch adds a statistic to track
> the minimum gradient (dT/dt) to the thermal zone
> stats/ folder.
>
> Samples:
>
> $ echo 1000 > emul_temp
> $ cat stats/min_gradient
> 0
> $ echo 2000 > emul_temp
> $ echo 1000 > emul_temp
> $ cat stats/min_gradient
> -3460
>
> Cc: "Rafael J. Wysocki" <rafael@kernel.org> (supporter:THERMAL)
> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> (supporter:THERMAL)
> Cc: Amit Kucheria <amitk@kernel.org> (reviewer:THERMAL)
> Cc: Zhang Rui <rui.zhang@intel.com> (reviewer:THERMAL)
> Cc: Jonathan Corbet <corbet@lwn.net> (maintainer:DOCUMENTATION)
> Cc: linux-pm@vger.kernel.org (open list:THERMAL)
> Cc: linux-doc@vger.kernel.org (open list:DOCUMENTATION)
> Cc: linux-kernel@vger.kernel.org (open list)
>
> Signed-off-by: Eduardo Valentin <eduval@amazon.com>

This can be easily folded into the previous patch IMO.

> ---
> .../driver-api/thermal/sysfs-api.rst | 1 +
> drivers/thermal/thermal_sysfs.c | 23 +++++++++++++++++++
> 2 files changed, 24 insertions(+)
>
> diff --git a/Documentation/driver-api/thermal/sysfs-api.rst b/Documentation/driver-api/thermal/sysfs-api.rst
> index 18140dbb1ce1..ed5e6ba4e0d7 100644
> --- a/Documentation/driver-api/thermal/sysfs-api.rst
> +++ b/Documentation/driver-api/thermal/sysfs-api.rst
> @@ -358,6 +358,7 @@ Thermal zone device sys I/F, created once it's registered::
> |---stats: Directory containing thermal zone device's stats
> |---stats/reset_tz_stats: Writes to this file resets the statistics.
> |---stats/max_gradient: The maximum recorded dT/dt in uC/ms.
> + |---stats/min_gradient: The minimum recorded dT/dt in uC/ms.
>
> Thermal cooling device sys I/F, created once it's registered::
>
> diff --git a/drivers/thermal/thermal_sysfs.c b/drivers/thermal/thermal_sysfs.c
> index aa28c1cae916..f89ec9a7e8c8 100644
> --- a/drivers/thermal/thermal_sysfs.c
> +++ b/drivers/thermal/thermal_sysfs.c
> @@ -542,6 +542,7 @@ static void destroy_trip_attrs(struct thermal_zone_device *tz)
> struct thermal_zone_device_stats {
> spinlock_t lock; /* protects this struct */
> s64 max_gradient;
> + s64 min_gradient;
> ktime_t last_time;
> };
>
> @@ -569,6 +570,10 @@ static void temperature_stats_update(struct thermal_zone_device *tz)
> /* update fastest temperature rise from our perspective */
> if (cur_gradient > stats->max_gradient)
> stats->max_gradient = cur_gradient;
> +
> + /* update fastest temperature decay from our perspective */
> + if (cur_gradient < stats->min_gradient)
> + stats->min_gradient = cur_gradient;
> }
>
> void thermal_zone_device_stats_update(struct thermal_zone_device *tz)
> @@ -595,6 +600,21 @@ static ssize_t max_gradient_show(struct device *dev,
> return ret;
> }
>
> +static ssize_t min_gradient_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct thermal_zone_device *tz = to_thermal_zone(dev);
> + struct thermal_zone_device_stats *stats = tz->stats;
> + int ret;
> +
> + spin_lock(&stats->lock);
> + temperature_stats_update(tz);
> + ret = snprintf(buf, PAGE_SIZE, "%lld\n", stats->min_gradient);
> + spin_unlock(&stats->lock);
> +
> + return ret;
> +}
> +
> static ssize_t
> reset_tz_stats_store(struct device *dev, struct device_attribute *attr,
> const char *buf, size_t count)
> @@ -604,6 +624,7 @@ reset_tz_stats_store(struct device *dev, struct device_attribute *attr,
>
> spin_lock(&stats->lock);
>
> + stats->min_gradient = 0;
> stats->max_gradient = 0;
> stats->last_time = ktime_get();
>
> @@ -612,10 +633,12 @@ reset_tz_stats_store(struct device *dev, struct device_attribute *attr,
> return count;
> }
>
> +static DEVICE_ATTR_RO(min_gradient);
> static DEVICE_ATTR_RO(max_gradient);
> static DEVICE_ATTR_WO(reset_tz_stats);
>
> static struct attribute *thermal_zone_device_stats_attrs[] = {
> + &dev_attr_min_gradient.attr,
> &dev_attr_max_gradient.attr,
> &dev_attr_reset_tz_stats.attr,
> NULL
> --
> 2.34.1
>