linux-kernel - Re: [PATCH V4] thermal: Add cooling device's statistics in sysfs

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Date:   Tue, 13 Mar 2018 15:02:51 +0800
From:   Zhang Rui <rui.zhang@...el.com>
To:     Viresh Kumar <viresh.kumar@...aro.org>,
        Eduardo Valentin <edubezval@...il.com>
Cc:     Vincent Guittot <vincent.guittot@...aro.org>,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org
Subject: Re: [PATCH V4] thermal: Add cooling device's statistics in sysfs

Hi, Viresh,

I will queue it for 4.17, with just one minor fix below.

On 二, 2018-01-16 at 15:22 +0530, Viresh Kumar wrote:
> 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" file shows the clock_t time 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  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@...aro.org>

[snip]

> +static void cooling_device_stats_setup(struct thermal_cooling_device
> *cdev)
> +{
> +	struct cooling_dev_stats *stats;
> +	unsigned long states;
> +	int var;
> +
> +	if (cdev->ops->get_max_state(cdev, &states))
> +		return;
> +
> +	states++; /* Total number of states is highest state + 1 */
> +
> +	var = sizeof(*stats);
> +	var += sizeof(*stats->time_in_state) * states;
> +	var += sizeof(*stats->trans_table) * states * states;
> +
> +	stats = kzalloc(var, GFP_KERNEL);
> +	if (!stats)
> +		return;
> +
> +	stats->time_in_state = (ktime_t *)(stats + 1);
> +	stats->trans_table = (unsigned int *)(stats->time_in_state +
> states);
> +	cdev->stats = stats;
> +	stats->last_time = ktime_get();
> +	stats->max_states = states;
> +	cdev->stats = stats;
> +

cdev->stats is set twice here, I will remove the first one.

thanks,
rui