[PATCH v2 0/3] devfreq: improve devfreq statistics counting

[PATCH v2 0/3] devfreq: improve devfreq statistics counting

[Kamil Konieczny]

Hi,

this patch series tries to improve devfreq statistics:

- do conversion to use 64-bit jiffies for storing elapsed time and prevent
  counters overflow,

- add ability to reset statistics using sysfs,

- move statistics data to separate structure for improved code
  readability and maintenance.

Changes in v2:
- added Acked-by to first patch
- dropped spinlock patch, there is mutex used for protecting stats data
- rewrite clearing statistics, suggested by Chanwoo Choi: reuse
  trans_stats sysfs file, any write to it will clear devfreq stats
- dropped change var name last_stat_updated
- squashed three last patches into one, as it turned out that freq_table
  from devfreq_profile is used by other drivers
- rebased on linux-next

Kamil Konieczny (3):
  devfreq: change time stats to 64-bit
  devfreq: add clearing transitions stats
  devfreq: move statistics to separate struct

 drivers/devfreq/devfreq.c | 86 +++++++++++++++++++++++++++------------
 include/linux/devfreq.h   | 31 ++++++++++----
 2 files changed, 81 insertions(+), 36 deletions(-)

-- 
2.24.0

[PATCH v2 1/3] devfreq: change time stats to 64-bit

[Kamil Konieczny]

Change time stats counting to bigger type by using 64-bit jiffies.
This will make devfreq stats code look similar to cpufreq stats and
prevents overflow (for HZ = 1000 after 49.7 days).

Signed-off-by: Kamil Konieczny <k.konieczny@samsung.com>
Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
---
Changes in v2:
 added Acked-by, rebased on linux-next

 drivers/devfreq/devfreq.c | 14 +++++++-------
 include/linux/devfreq.h   |  4 ++--
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index bdeb4189c978..0e2030403e4a 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -199,10 +199,10 @@ static int set_freq_table(struct devfreq *devfreq)
 int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
 {
 	int lev, prev_lev, ret = 0;
-	unsigned long cur_time;
+	unsigned long long cur_time;
 
 	lockdep_assert_held(&devfreq->lock);
-	cur_time = jiffies;
+	cur_time = get_jiffies_64();
 
 	/* Immediately exit if previous_freq is not initialized yet. */
 	if (!devfreq->previous_freq)
@@ -525,7 +525,7 @@ void devfreq_monitor_resume(struct devfreq *devfreq)
 			msecs_to_jiffies(devfreq->profile->polling_ms));
 
 out_update:
-	devfreq->last_stat_updated = jiffies;
+	devfreq->last_stat_updated = get_jiffies_64();
 	devfreq->stop_polling = false;
 
 	if (devfreq->profile->get_cur_freq &&
@@ -748,7 +748,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
 
 	devfreq->time_in_state = devm_kcalloc(&devfreq->dev,
 			devfreq->profile->max_state,
-			sizeof(unsigned long),
+			sizeof(*devfreq->time_in_state),
 			GFP_KERNEL);
 	if (!devfreq->time_in_state) {
 		mutex_unlock(&devfreq->lock);
@@ -756,7 +756,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
 		goto err_devfreq;
 	}
 
-	devfreq->last_stat_updated = jiffies;
+	devfreq->last_stat_updated = get_jiffies_64();
 
 	srcu_init_notifier_head(&devfreq->transition_notifier_list);
 
@@ -1470,8 +1470,8 @@ static ssize_t trans_stat_show(struct device *dev,
 		for (j = 0; j < max_state; j++)
 			len += sprintf(buf + len, "%10u",
 				devfreq->trans_table[(i * max_state) + j]);
-		len += sprintf(buf + len, "%10u\n",
-			jiffies_to_msecs(devfreq->time_in_state[i]));
+		len += sprintf(buf + len, "%10llu\n", (u64)
+			jiffies64_to_msecs(devfreq->time_in_state[i]));
 	}
 
 	len += sprintf(buf + len, "Total transition : %u\n",
diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
index 2bae9ed3c783..b81a86e47fb9 100644
--- a/include/linux/devfreq.h
+++ b/include/linux/devfreq.h
@@ -174,8 +174,8 @@ struct devfreq {
 	/* information for device frequency transition */
 	unsigned int total_trans;
 	unsigned int *trans_table;
-	unsigned long *time_in_state;
-	unsigned long last_stat_updated;
+	u64 *time_in_state;
+	unsigned long long last_stat_updated;
 
 	struct srcu_notifier_head transition_notifier_list;
 };
-- 
2.24.0

[PATCH v2 2/3] devfreq: add clearing transitions stats

[Kamil Konieczny]

Add clearing transition table and time in states devfreq statistics
by writing to trans_stat file in devfreq sysfs.

Signed-off-by: Kamil Konieczny <k.konieczny@samsung.com>
---
Changes in v2:
 instead of creating new sysfs file, add new functionality to trans_stat
 and clear stats when anything is writen to it

 drivers/devfreq/devfreq.c | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 0e2030403e4a..901af3b66a76 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -1478,7 +1478,27 @@ static ssize_t trans_stat_show(struct device *dev,
 					devfreq->total_trans);
 	return len;
 }
-static DEVICE_ATTR_RO(trans_stat);
+
+static ssize_t trans_stat_store(struct device *dev,
+				struct device_attribute *attr,
+				const char *buf, size_t count)
+{
+	struct devfreq *df = to_devfreq(dev);
+	unsigned int cnt = df->profile->max_state;
+
+	if (cnt == 0)
+		return count;
+
+	mutex_lock(&df->lock);
+	memset(df->time_in_state, 0, cnt * sizeof(u64));
+	memset(df->trans_table, 0, cnt * cnt * sizeof(int));
+	df->last_stat_updated = get_jiffies_64();
+	df->total_trans = 0;
+	mutex_unlock(&df->lock);
+
+	return count;
+}
+static DEVICE_ATTR_RW(trans_stat);
 
 static struct attribute *devfreq_attrs[] = {
 	&dev_attr_name.attr,
-- 
2.24.0

[PATCH v2 3/3] devfreq: move statistics to separate struct

[Kamil Konieczny]

Count time and transitions between devfreq frequencies in separate struct
for improved code readability and maintenance.

Signed-off-by: Kamil Konieczny <k.konieczny@samsung.com>
---
Changes in v2:
 squash three patches into one, do not modify devfreq_profile and separate stats
 into devfreq_stats

 drivers/devfreq/devfreq.c | 68 +++++++++++++++++++++++----------------
 include/linux/devfreq.h   | 31 ++++++++++++------
 2 files changed, 62 insertions(+), 37 deletions(-)

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 901af3b66a76..4d50c8f10bd2 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -198,6 +198,7 @@ static int set_freq_table(struct devfreq *devfreq)
  */
 int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
 {
+	struct devfreq_stats *stats = devfreq->stats;
 	int lev, prev_lev, ret = 0;
 	unsigned long long cur_time;
 
@@ -214,8 +215,8 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
 		goto out;
 	}
 
-	devfreq->time_in_state[prev_lev] +=
-			 cur_time - devfreq->last_stat_updated;
+	stats->time_in_state[prev_lev] +=
+			 cur_time - stats->last_stat_updated;
 
 	lev = devfreq_get_freq_level(devfreq, freq);
 	if (lev < 0) {
@@ -224,13 +225,12 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
 	}
 
 	if (lev != prev_lev) {
-		devfreq->trans_table[(prev_lev *
-				devfreq->profile->max_state) + lev]++;
-		devfreq->total_trans++;
+		stats->trans_table[(prev_lev * stats->max_state) + lev]++;
+		stats->total_trans++;
 	}
 
 out:
-	devfreq->last_stat_updated = cur_time;
+	stats->last_stat_updated = cur_time;
 	return ret;
 }
 EXPORT_SYMBOL(devfreq_update_status);
@@ -525,7 +525,7 @@ void devfreq_monitor_resume(struct devfreq *devfreq)
 			msecs_to_jiffies(devfreq->profile->polling_ms));
 
 out_update:
-	devfreq->last_stat_updated = get_jiffies_64();
+	devfreq->stats->last_stat_updated = get_jiffies_64();
 	devfreq->stop_polling = false;
 
 	if (devfreq->profile->get_cur_freq &&
@@ -735,28 +735,38 @@ struct devfreq *devfreq_add_device(struct device *dev,
 		goto err_out;
 	}
 
-	devfreq->trans_table = devm_kzalloc(&devfreq->dev,
+	devfreq->stats = devm_kzalloc(&devfreq->dev, sizeof(*devfreq->stats),
+				      GFP_KERNEL);
+	if (!devfreq->stats) {
+		mutex_unlock(&devfreq->lock);
+		err = -ENOMEM;
+		goto err_devfreq;
+	}
+
+	devfreq->stats->freq_table = devfreq->profile->freq_table;
+	devfreq->stats->max_state = devfreq->profile->max_state;
+	devfreq->stats->trans_table = devm_kzalloc(&devfreq->dev,
 			array3_size(sizeof(unsigned int),
-				    devfreq->profile->max_state,
-				    devfreq->profile->max_state),
+				    devfreq->stats->max_state,
+				    devfreq->stats->max_state),
 			GFP_KERNEL);
-	if (!devfreq->trans_table) {
+	if (!devfreq->stats->trans_table) {
 		mutex_unlock(&devfreq->lock);
 		err = -ENOMEM;
 		goto err_devfreq;
 	}
 
-	devfreq->time_in_state = devm_kcalloc(&devfreq->dev,
-			devfreq->profile->max_state,
-			sizeof(*devfreq->time_in_state),
+	devfreq->stats->time_in_state = devm_kcalloc(&devfreq->dev,
+			devfreq->stats->max_state,
+			sizeof(*devfreq->stats->time_in_state),
 			GFP_KERNEL);
-	if (!devfreq->time_in_state) {
+	if (!devfreq->stats->time_in_state) {
 		mutex_unlock(&devfreq->lock);
 		err = -ENOMEM;
 		goto err_devfreq;
 	}
 
-	devfreq->last_stat_updated = get_jiffies_64();
+	devfreq->stats->last_stat_updated = get_jiffies_64();
 
 	srcu_init_notifier_head(&devfreq->transition_notifier_list);
 
@@ -1435,9 +1445,10 @@ static ssize_t trans_stat_show(struct device *dev,
 			       struct device_attribute *attr, char *buf)
 {
 	struct devfreq *devfreq = to_devfreq(dev);
+	struct devfreq_stats *stats = devfreq->stats;
+	unsigned int max_state = stats->max_state;
 	ssize_t len;
 	int i, j;
-	unsigned int max_state = devfreq->profile->max_state;
 
 	if (max_state == 0)
 		return sprintf(buf, "Not Supported.\n");
@@ -1454,28 +1465,28 @@ static ssize_t trans_stat_show(struct device *dev,
 	len += sprintf(buf + len, "           :");
 	for (i = 0; i < max_state; i++)
 		len += sprintf(buf + len, "%10lu",
-				devfreq->profile->freq_table[i]);
+				stats->freq_table[i]);
 
 	len += sprintf(buf + len, "   time(ms)\n");
 
 	for (i = 0; i < max_state; i++) {
-		if (devfreq->profile->freq_table[i]
+		if (stats->freq_table[i]
 					== devfreq->previous_freq) {
 			len += sprintf(buf + len, "*");
 		} else {
 			len += sprintf(buf + len, " ");
 		}
 		len += sprintf(buf + len, "%10lu:",
-				devfreq->profile->freq_table[i]);
+				stats->freq_table[i]);
 		for (j = 0; j < max_state; j++)
 			len += sprintf(buf + len, "%10u",
-				devfreq->trans_table[(i * max_state) + j]);
+				stats->trans_table[(i * max_state) + j]);
 		len += sprintf(buf + len, "%10llu\n", (u64)
-			jiffies64_to_msecs(devfreq->time_in_state[i]));
+			jiffies64_to_msecs(stats->time_in_state[i]));
 	}
 
 	len += sprintf(buf + len, "Total transition : %u\n",
-					devfreq->total_trans);
+					stats->total_trans);
 	return len;
 }
 
@@ -1484,16 +1495,17 @@ static ssize_t trans_stat_store(struct device *dev,
 				const char *buf, size_t count)
 {
 	struct devfreq *df = to_devfreq(dev);
-	unsigned int cnt = df->profile->max_state;
+	struct devfreq_stats *stats = df->stats;
+	unsigned int cnt = stats->max_state;
 
 	if (cnt == 0)
 		return count;
 
 	mutex_lock(&df->lock);
-	memset(df->time_in_state, 0, cnt * sizeof(u64));
-	memset(df->trans_table, 0, cnt * cnt * sizeof(int));
-	df->last_stat_updated = get_jiffies_64();
-	df->total_trans = 0;
+	memset(stats->time_in_state, 0, cnt * sizeof(u64));
+	memset(stats->trans_table, 0, cnt * cnt * sizeof(int));
+	stats->last_stat_updated = get_jiffies_64();
+	stats->total_trans = 0;
 	mutex_unlock(&df->lock);
 
 	return count;
diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
index b81a86e47fb9..2715719924e7 100644
--- a/include/linux/devfreq.h
+++ b/include/linux/devfreq.h
@@ -106,6 +106,25 @@ struct devfreq_dev_profile {
 	unsigned int max_state;
 };
 
+/**
+ * struct devfreq_stats - Devfreq's transitions stats counters
+ * @freq_table:		List of frequencies in ascending order.
+ * @max_state:		The size of freq_table.
+ * @total_trans:	Number of devfreq transitions.
+ * @trans_table:	Statistics of devfreq transitions.
+ * @time_in_state:	Statistics of devfreq states.
+ * @last_stat_updated:	The last time stats were updated.
+ */
+struct devfreq_stats {
+	unsigned long *freq_table;
+	unsigned int max_state;
+
+	unsigned int total_trans;
+	unsigned int *trans_table;
+	u64 *time_in_state;
+	unsigned long long last_stat_updated;
+};
+
 /**
  * struct devfreq - Device devfreq structure
  * @node:	list node - contains the devices with devfreq that have been
@@ -131,10 +150,7 @@ struct devfreq_dev_profile {
  * @suspend_freq:	 frequency of a device set during suspend phase.
  * @resume_freq:	 frequency of a device set in resume phase.
  * @suspend_count:	 suspend requests counter for a device.
- * @total_trans:	Number of devfreq transitions
- * @trans_table:	Statistics of devfreq transitions
- * @time_in_state:	Statistics of devfreq states
- * @last_stat_updated:	The last time stat updated
+ * @stats:	Statistics of devfreq transitions and states times
  * @transition_notifier_list: list head of DEVFREQ_TRANSITION_NOTIFIER notifier
  *
  * This structure stores the devfreq information for a give device.
@@ -171,11 +187,8 @@ struct devfreq {
 	unsigned long resume_freq;
 	atomic_t suspend_count;
 
-	/* information for device frequency transition */
-	unsigned int total_trans;
-	unsigned int *trans_table;
-	u64 *time_in_state;
-	unsigned long long last_stat_updated;
+	/* information for device frequency transitions */
+	struct devfreq_stats *stats;
 
 	struct srcu_notifier_head transition_notifier_list;
 };
-- 
2.24.0

Re: [PATCH v2 1/3] devfreq: change time stats to 64-bit

[Chanwoo Choi]

On 12/5/19 12:00 AM, Kamil Konieczny wrote:
> Change time stats counting to bigger type by using 64-bit jiffies.
> This will make devfreq stats code look similar to cpufreq stats and
> prevents overflow (for HZ = 1000 after 49.7 days).
> 
> Signed-off-by: Kamil Konieczny <k.konieczny@samsung.com>
> Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
> ---
> Changes in v2:
>  added Acked-by, rebased on linux-next
> 
>  drivers/devfreq/devfreq.c | 14 +++++++-------
>  include/linux/devfreq.h   |  4 ++--
>  2 files changed, 9 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index bdeb4189c978..0e2030403e4a 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -199,10 +199,10 @@ static int set_freq_table(struct devfreq *devfreq)
>  int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>  {
>  	int lev, prev_lev, ret = 0;
> -	unsigned long cur_time;
> +	unsigned long long cur_time;

It looks better to use 'u64' instead of 'unsigned long long'.
Because get_jiffies_u64 has 'u64' return type.

>  
>  	lockdep_assert_held(&devfreq->lock);
> -	cur_time = jiffies;
> +	cur_time = get_jiffies_64();
>  
>  	/* Immediately exit if previous_freq is not initialized yet. */
>  	if (!devfreq->previous_freq)
> @@ -525,7 +525,7 @@ void devfreq_monitor_resume(struct devfreq *devfreq)
>  			msecs_to_jiffies(devfreq->profile->polling_ms));
>  
>  out_update:
> -	devfreq->last_stat_updated = jiffies;
> +	devfreq->last_stat_updated = get_jiffies_64();
>  	devfreq->stop_polling = false;
>  
>  	if (devfreq->profile->get_cur_freq &&
> @@ -748,7 +748,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
>  
>  	devfreq->time_in_state = devm_kcalloc(&devfreq->dev,
>  			devfreq->profile->max_state,
> -			sizeof(unsigned long),
> +			sizeof(*devfreq->time_in_state),
>  			GFP_KERNEL);
>  	if (!devfreq->time_in_state) {
>  		mutex_unlock(&devfreq->lock);
> @@ -756,7 +756,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
>  		goto err_devfreq;
>  	}
>  
> -	devfreq->last_stat_updated = jiffies;
> +	devfreq->last_stat_updated = get_jiffies_64();
>  
>  	srcu_init_notifier_head(&devfreq->transition_notifier_list);
>  
> @@ -1470,8 +1470,8 @@ static ssize_t trans_stat_show(struct device *dev,
>  		for (j = 0; j < max_state; j++)
>  			len += sprintf(buf + len, "%10u",
>  				devfreq->trans_table[(i * max_state) + j]);
> -		len += sprintf(buf + len, "%10u\n",
> -			jiffies_to_msecs(devfreq->time_in_state[i]));
> +		len += sprintf(buf + len, "%10llu\n", (u64)
> +			jiffies64_to_msecs(devfreq->time_in_state[i]));
>  	}
>  
>  	len += sprintf(buf + len, "Total transition : %u\n",
> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
> index 2bae9ed3c783..b81a86e47fb9 100644
> --- a/include/linux/devfreq.h
> +++ b/include/linux/devfreq.h
> @@ -174,8 +174,8 @@ struct devfreq {
>  	/* information for device frequency transition */
>  	unsigned int total_trans;
>  	unsigned int *trans_table;
> -	unsigned long *time_in_state;
> -	unsigned long last_stat_updated;
> +	u64 *time_in_state;
> +	unsigned long long last_stat_updated;

ditto. 'unsigned long long' -> 'u64'.

>  
>  	struct srcu_notifier_head transition_notifier_list;
>  };
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics

Re: [PATCH v2 3/3] devfreq: move statistics to separate struct

[Matthias Kaehlcke]

Hi,

On Wed, Dec 04, 2019 at 04:00:18PM +0100, Kamil Konieczny wrote:
> Count time and transitions between devfreq frequencies in separate struct
> for improved code readability and maintenance.
> 
> Signed-off-by: Kamil Konieczny <k.konieczny@samsung.com>
> ---
> Changes in v2:
>  squash three patches into one, do not modify devfreq_profile and separate stats
>  into devfreq_stats
> 
>  drivers/devfreq/devfreq.c | 68 +++++++++++++++++++++++----------------
>  include/linux/devfreq.h   | 31 ++++++++++++------
>  2 files changed, 62 insertions(+), 37 deletions(-)
> 
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 901af3b66a76..4d50c8f10bd2 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -198,6 +198,7 @@ static int set_freq_table(struct devfreq *devfreq)
>   */
>  int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>  {
> +	struct devfreq_stats *stats = devfreq->stats;
>  	int lev, prev_lev, ret = 0;
>  	unsigned long long cur_time;
>  
> @@ -214,8 +215,8 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>  		goto out;
>  	}
>  
> -	devfreq->time_in_state[prev_lev] +=
> -			 cur_time - devfreq->last_stat_updated;
> +	stats->time_in_state[prev_lev] +=
> +			 cur_time - stats->last_stat_updated;
>  
>  	lev = devfreq_get_freq_level(devfreq, freq);
>  	if (lev < 0) {
> @@ -224,13 +225,12 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>  	}
>  
>  	if (lev != prev_lev) {
> -		devfreq->trans_table[(prev_lev *
> -				devfreq->profile->max_state) + lev]++;
> -		devfreq->total_trans++;
> +		stats->trans_table[(prev_lev * stats->max_state) + lev]++;
> +		stats->total_trans++;
>  	}
>  
>  out:
> -	devfreq->last_stat_updated = cur_time;
> +	stats->last_stat_updated = cur_time;
>  	return ret;
>  }
>  EXPORT_SYMBOL(devfreq_update_status);
> @@ -525,7 +525,7 @@ void devfreq_monitor_resume(struct devfreq *devfreq)
>  			msecs_to_jiffies(devfreq->profile->polling_ms));
>  
>  out_update:
> -	devfreq->last_stat_updated = get_jiffies_64();
> +	devfreq->stats->last_stat_updated = get_jiffies_64();
>  	devfreq->stop_polling = false;
>  
>  	if (devfreq->profile->get_cur_freq &&
> @@ -735,28 +735,38 @@ struct devfreq *devfreq_add_device(struct device *dev,
>  		goto err_out;
>  	}
>  
> -	devfreq->trans_table = devm_kzalloc(&devfreq->dev,
> +	devfreq->stats = devm_kzalloc(&devfreq->dev, sizeof(*devfreq->stats),
> +				      GFP_KERNEL);
> +	if (!devfreq->stats) {
> +		mutex_unlock(&devfreq->lock);
> +		err = -ENOMEM;
> +		goto err_devfreq;
> +	}
> +
> +	devfreq->stats->freq_table = devfreq->profile->freq_table;
> +	devfreq->stats->max_state = devfreq->profile->max_state;
> +	devfreq->stats->trans_table = devm_kzalloc(&devfreq->dev,
>  			array3_size(sizeof(unsigned int),
> -				    devfreq->profile->max_state,
> -				    devfreq->profile->max_state),
> +				    devfreq->stats->max_state,
> +				    devfreq->stats->max_state),
>  			GFP_KERNEL);
> -	if (!devfreq->trans_table) {
> +	if (!devfreq->stats->trans_table) {
>  		mutex_unlock(&devfreq->lock);
>  		err = -ENOMEM;
>  		goto err_devfreq;
>  	}
>  
> -	devfreq->time_in_state = devm_kcalloc(&devfreq->dev,
> -			devfreq->profile->max_state,
> -			sizeof(*devfreq->time_in_state),
> +	devfreq->stats->time_in_state = devm_kcalloc(&devfreq->dev,
> +			devfreq->stats->max_state,
> +			sizeof(*devfreq->stats->time_in_state),
>  			GFP_KERNEL);
> -	if (!devfreq->time_in_state) {
> +	if (!devfreq->stats->time_in_state) {
>  		mutex_unlock(&devfreq->lock);
>  		err = -ENOMEM;
>  		goto err_devfreq;
>  	}
>  
> -	devfreq->last_stat_updated = get_jiffies_64();
> +	devfreq->stats->last_stat_updated = get_jiffies_64();
>  
>  	srcu_init_notifier_head(&devfreq->transition_notifier_list);
>  
> @@ -1435,9 +1445,10 @@ static ssize_t trans_stat_show(struct device *dev,
>  			       struct device_attribute *attr, char *buf)
>  {
>  	struct devfreq *devfreq = to_devfreq(dev);
> +	struct devfreq_stats *stats = devfreq->stats;
> +	unsigned int max_state = stats->max_state;
>  	ssize_t len;
>  	int i, j;
> -	unsigned int max_state = devfreq->profile->max_state;
>  
>  	if (max_state == 0)
>  		return sprintf(buf, "Not Supported.\n");
> @@ -1454,28 +1465,28 @@ static ssize_t trans_stat_show(struct device *dev,
>  	len += sprintf(buf + len, "           :");
>  	for (i = 0; i < max_state; i++)
>  		len += sprintf(buf + len, "%10lu",
> -				devfreq->profile->freq_table[i]);
> +				stats->freq_table[i]);
>  
>  	len += sprintf(buf + len, "   time(ms)\n");
>  
>  	for (i = 0; i < max_state; i++) {
> -		if (devfreq->profile->freq_table[i]
> +		if (stats->freq_table[i]
>  					== devfreq->previous_freq) {
>  			len += sprintf(buf + len, "*");
>  		} else {
>  			len += sprintf(buf + len, " ");
>  		}
>  		len += sprintf(buf + len, "%10lu:",
> -				devfreq->profile->freq_table[i]);
> +				stats->freq_table[i]);
>  		for (j = 0; j < max_state; j++)
>  			len += sprintf(buf + len, "%10u",
> -				devfreq->trans_table[(i * max_state) + j]);
> +				stats->trans_table[(i * max_state) + j]);
>  		len += sprintf(buf + len, "%10llu\n", (u64)
> -			jiffies64_to_msecs(devfreq->time_in_state[i]));
> +			jiffies64_to_msecs(stats->time_in_state[i]));
>  	}
>  
>  	len += sprintf(buf + len, "Total transition : %u\n",
> -					devfreq->total_trans);
> +					stats->total_trans);
>  	return len;
>  }
>  
> @@ -1484,16 +1495,17 @@ static ssize_t trans_stat_store(struct device *dev,
>  				const char *buf, size_t count)
>  {
>  	struct devfreq *df = to_devfreq(dev);
> -	unsigned int cnt = df->profile->max_state;
> +	struct devfreq_stats *stats = df->stats;
> +	unsigned int cnt = stats->max_state;
>  
>  	if (cnt == 0)
>  		return count;
>  
>  	mutex_lock(&df->lock);
> -	memset(df->time_in_state, 0, cnt * sizeof(u64));
> -	memset(df->trans_table, 0, cnt * cnt * sizeof(int));
> -	df->last_stat_updated = get_jiffies_64();
> -	df->total_trans = 0;
> +	memset(stats->time_in_state, 0, cnt * sizeof(u64));
> +	memset(stats->trans_table, 0, cnt * cnt * sizeof(int));
> +	stats->last_stat_updated = get_jiffies_64();
> +	stats->total_trans = 0;
>  	mutex_unlock(&df->lock);
>  
>  	return count;
> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
> index b81a86e47fb9..2715719924e7 100644
> --- a/include/linux/devfreq.h
> +++ b/include/linux/devfreq.h
> @@ -106,6 +106,25 @@ struct devfreq_dev_profile {
>  	unsigned int max_state;
>  };
>  
> +/**
> + * struct devfreq_stats - Devfreq's transitions stats counters
> + * @freq_table:		List of frequencies in ascending order.
> + * @max_state:		The size of freq_table.
> + * @total_trans:	Number of devfreq transitions.
> + * @trans_table:	Statistics of devfreq transitions.
> + * @time_in_state:	Statistics of devfreq states.
> + * @last_stat_updated:	The last time stats were updated.
> + */
> +struct devfreq_stats {
> +	unsigned long *freq_table;

nit: trans_stat_show() is the only place where 'freq_table' is
used. Instead of 'duplicating' it (I know, it's just a pointer)
you could use a local pointer 'freq_table' in trans_stat_show().

> +	unsigned int max_state;

nit: max_state is also a bit of a corner case. It's not really a 'stat' and
it is already available in struct devfreq_dev_profile, it doesn't seem a
huge inconvenient to take it from there.

> +
> +	unsigned int total_trans;
> +	unsigned int *trans_table;
> +	u64 *time_in_state;
> +	unsigned long long last_stat_updated;

nit: the name 'last_stat_updated' is somewhat redundant, since the
field is part of a struct called 'devfreq_stats'. 'last_updated' or
'last_update' would be concise enough IMO.

> +};
> +
>  /**
>   * struct devfreq - Device devfreq structure
>   * @node:	list node - contains the devices with devfreq that have been
> @@ -131,10 +150,7 @@ struct devfreq_dev_profile {
>   * @suspend_freq:	 frequency of a device set during suspend phase.
>   * @resume_freq:	 frequency of a device set in resume phase.
>   * @suspend_count:	 suspend requests counter for a device.
> - * @total_trans:	Number of devfreq transitions
> - * @trans_table:	Statistics of devfreq transitions
> - * @time_in_state:	Statistics of devfreq states
> - * @last_stat_updated:	The last time stat updated
> + * @stats:	Statistics of devfreq transitions and states times
>   * @transition_notifier_list: list head of DEVFREQ_TRANSITION_NOTIFIER notifier
>   *
>   * This structure stores the devfreq information for a give device.
> @@ -171,11 +187,8 @@ struct devfreq {
>  	unsigned long resume_freq;
>  	atomic_t suspend_count;
>  
> -	/* information for device frequency transition */
> -	unsigned int total_trans;
> -	unsigned int *trans_table;
> -	u64 *time_in_state;
> -	unsigned long long last_stat_updated;
> +	/* information for device frequency transitions */
> +	struct devfreq_stats *stats;
>  
>  	struct srcu_notifier_head transition_notifier_list;
>  };

My comments above are just suggestions:

Reviewed-by: Matthias Kaehlcke <mka@chromium.org>

Re: [PATCH v2 2/3] devfreq: add clearing transitions stats

[Chanwoo Choi]

On 12/5/19 12:00 AM, Kamil Konieczny wrote:
> Add clearing transition table and time in states devfreq statistics
> by writing to trans_stat file in devfreq sysfs.

Have to add command example how to reset the trans_stat via sysfs
on patch description.

And, have to add how to do it on documentation file as following:
On next version, please contain the following modification with this patch.

diff --git a/Documentation/ABI/testing/sysfs-class-devfreq b/Documentation/ABI/testing/sysfs-class-devfreq
index 75897e2fde43..c172ff838643 100644
--- a/Documentation/ABI/testing/sysfs-class-devfreq
+++ b/Documentation/ABI/testing/sysfs-class-devfreq
@@ -60,7 +60,10 @@ Description:
                the number of transitions between states.
                In order to activate this ABI, the devfreq target device
                driver should provide the list of available frequencies
-               with its profile.
+               with its profile. If need to reset the statistics of devfreq
+               behavior on a specific device, enter 0(zero) to 'trans_stat'
+               as following:
+                       echo 0 > /sys/class/devfreq/.../trans_stat
 
 What:          /sys/class/devfreq/.../userspace/set_freq
 Date:          September 2011


> 
> Signed-off-by: Kamil Konieczny <k.konieczny@samsung.com>
> ---
> Changes in v2:
>  instead of creating new sysfs file, add new functionality to trans_stat
>  and clear stats when anything is writen to it
> 
>  drivers/devfreq/devfreq.c | 22 +++++++++++++++++++++-
>  1 file changed, 21 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 0e2030403e4a..901af3b66a76 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -1478,7 +1478,27 @@ static ssize_t trans_stat_show(struct device *dev,
>  					devfreq->total_trans);
>  	return len;
>  }
> -static DEVICE_ATTR_RO(trans_stat);
> +
> +static ssize_t trans_stat_store(struct device *dev,
> +				struct device_attribute *attr,
> +				const char *buf, size_t count)
> +{
> +	struct devfreq *df = to_devfreq(dev);
> +	unsigned int cnt = df->profile->max_state;
> +

Why don't you check the input value is whether value is 0(zero) or not?
If user enter the any value to 'trans_stat', devfreq core
reset the statistics data. I want to decide the fixed value
for the reset as following:

	echo 0 > /sys/class/devfreq/devfreqX/trans_stat

> +	if (cnt == 0)
> +		return count;
> +
> +	mutex_lock(&df->lock);
> +	memset(df->time_in_state, 0, cnt * sizeof(u64));
> +	memset(df->trans_table, 0, cnt * cnt * sizeof(int));
> +	df->last_stat_updated = get_jiffies_64();
> +	df->total_trans = 0;
> +	mutex_unlock(&df->lock);
> +
> +	return count;
> +}
> +static DEVICE_ATTR_RW(trans_stat);
>  
>  static struct attribute *devfreq_attrs[] = {
>  	&dev_attr_name.attr,
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics

Re: [PATCH v2 3/3] devfreq: move statistics to separate struct

[Chanwoo Choi]

On 12/5/19 12:00 AM, Kamil Konieczny wrote:
> Count time and transitions between devfreq frequencies in separate struct
> for improved code readability and maintenance.
> 
> Signed-off-by: Kamil Konieczny <k.konieczny@samsung.com>
> ---
> Changes in v2:
>  squash three patches into one, do not modify devfreq_profile and separate stats
>  into devfreq_stats
> 
>  drivers/devfreq/devfreq.c | 68 +++++++++++++++++++++++----------------
>  include/linux/devfreq.h   | 31 ++++++++++++------
>  2 files changed, 62 insertions(+), 37 deletions(-)
> 
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 901af3b66a76..4d50c8f10bd2 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -198,6 +198,7 @@ static int set_freq_table(struct devfreq *devfreq)
>   */
>  int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>  {
> +	struct devfreq_stats *stats = devfreq->stats;
>  	int lev, prev_lev, ret = 0;
>  	unsigned long long cur_time;
>  
> @@ -214,8 +215,8 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>  		goto out;
>  	}
>  
> -	devfreq->time_in_state[prev_lev] +=
> -			 cur_time - devfreq->last_stat_updated;
> +	stats->time_in_state[prev_lev] +=
> +			 cur_time - stats->last_stat_updated;
>  
>  	lev = devfreq_get_freq_level(devfreq, freq);
>  	if (lev < 0) {
> @@ -224,13 +225,12 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>  	}
>  
>  	if (lev != prev_lev) {
> -		devfreq->trans_table[(prev_lev *
> -				devfreq->profile->max_state) + lev]++;
> -		devfreq->total_trans++;
> +		stats->trans_table[(prev_lev * stats->max_state) + lev]++;
> +		stats->total_trans++;
>  	}
>  
>  out:
> -	devfreq->last_stat_updated = cur_time;
> +	stats->last_stat_updated = cur_time;
>  	return ret;
>  }
>  EXPORT_SYMBOL(devfreq_update_status);
> @@ -525,7 +525,7 @@ void devfreq_monitor_resume(struct devfreq *devfreq)
>  			msecs_to_jiffies(devfreq->profile->polling_ms));
>  
>  out_update:
> -	devfreq->last_stat_updated = get_jiffies_64();
> +	devfreq->stats->last_stat_updated = get_jiffies_64();
>  	devfreq->stop_polling = false;
>  
>  	if (devfreq->profile->get_cur_freq &&
> @@ -735,28 +735,38 @@ struct devfreq *devfreq_add_device(struct device *dev,
>  		goto err_out;
>  	}
>  
> -	devfreq->trans_table = devm_kzalloc(&devfreq->dev,
> +	devfreq->stats = devm_kzalloc(&devfreq->dev, sizeof(*devfreq->stats),
> +				      GFP_KERNEL);

Each devfreq has only one stats structure always. Don't need to define
it with pointer type. It is enough to define as following without pointer type:

	struct devfreq_stats stats;


> +	if (!devfreq->stats) {
> +		mutex_unlock(&devfreq->lock);
> +		err = -ENOMEM;
> +		goto err_devfreq;
> +	}
> +
> +	devfreq->stats->freq_table = devfreq->profile->freq_table;
> +	devfreq->stats->max_state = devfreq->profile->max_state;
> +	devfreq->stats->trans_table = devm_kzalloc(&devfreq->dev,
>  			array3_size(sizeof(unsigned int),
> -				    devfreq->profile->max_state,
> -				    devfreq->profile->max_state),
> +				    devfreq->stats->max_state,
> +				    devfreq->stats->max_state),
>  			GFP_KERNEL);
> -	if (!devfreq->trans_table) {
> +	if (!devfreq->stats->trans_table) {
>  		mutex_unlock(&devfreq->lock);
>  		err = -ENOMEM;
>  		goto err_devfreq;
>  	}
>  
> -	devfreq->time_in_state = devm_kcalloc(&devfreq->dev,
> -			devfreq->profile->max_state,
> -			sizeof(*devfreq->time_in_state),
> +	devfreq->stats->time_in_state = devm_kcalloc(&devfreq->dev,
> +			devfreq->stats->max_state,
> +			sizeof(*devfreq->stats->time_in_state),
>  			GFP_KERNEL);

Actually, this patch will be conflict with patch[1].
[1] https://www.spinics.net/lists/arm-kernel/msg768822.html

First of all, I have to merge patches[1][2] for the devfreq pm-qos
during v5.5-rc period. It requires the linux-pm's maintainer.
[2] https://www.spinics.net/lists/arm-kernel/msg769761.html

After finishing the job[1][2], I'll merge this patch
if finished the review of this patch. Just share the possible merge
conflict to you.


> -	if (!devfreq->time_in_state) {
> +	if (!devfreq->stats->time_in_state) {
>  		mutex_unlock(&devfreq->lock);
>  		err = -ENOMEM;
>  		goto err_devfreq;
>  	}
>  
> -	devfreq->last_stat_updated = get_jiffies_64();
> +	devfreq->stats->last_stat_updated = get_jiffies_64();
>  
>  	srcu_init_notifier_head(&devfreq->transition_notifier_list);
>  
> @@ -1435,9 +1445,10 @@ static ssize_t trans_stat_show(struct device *dev,
>  			       struct device_attribute *attr, char *buf)
>  {
>  	struct devfreq *devfreq = to_devfreq(dev);
> +	struct devfreq_stats *stats = devfreq->stats;
> +	unsigned int max_state = stats->max_state;
>  	ssize_t len;
>  	int i, j;
> -	unsigned int max_state = devfreq->profile->max_state;
>  
>  	if (max_state == 0)
>  		return sprintf(buf, "Not Supported.\n");
> @@ -1454,28 +1465,28 @@ static ssize_t trans_stat_show(struct device *dev,
>  	len += sprintf(buf + len, "           :");
>  	for (i = 0; i < max_state; i++)
>  		len += sprintf(buf + len, "%10lu",
> -				devfreq->profile->freq_table[i]);
> +				stats->freq_table[i]);
>  
>  	len += sprintf(buf + len, "   time(ms)\n");
>  
>  	for (i = 0; i < max_state; i++) {
> -		if (devfreq->profile->freq_table[i]
> +		if (stats->freq_table[i]
>  					== devfreq->previous_freq) {
>  			len += sprintf(buf + len, "*");
>  		} else {
>  			len += sprintf(buf + len, " ");
>  		}
>  		len += sprintf(buf + len, "%10lu:",
> -				devfreq->profile->freq_table[i]);
> +				stats->freq_table[i]);
>  		for (j = 0; j < max_state; j++)
>  			len += sprintf(buf + len, "%10u",
> -				devfreq->trans_table[(i * max_state) + j]);
> +				stats->trans_table[(i * max_state) + j]);
>  		len += sprintf(buf + len, "%10llu\n", (u64)
> -			jiffies64_to_msecs(devfreq->time_in_state[i]));
> +			jiffies64_to_msecs(stats->time_in_state[i]));
>  	}
>  
>  	len += sprintf(buf + len, "Total transition : %u\n",
> -					devfreq->total_trans);
> +					stats->total_trans);
>  	return len;
>  }
>  
> @@ -1484,16 +1495,17 @@ static ssize_t trans_stat_store(struct device *dev,
>  				const char *buf, size_t count)
>  {
>  	struct devfreq *df = to_devfreq(dev);
> -	unsigned int cnt = df->profile->max_state;
> +	struct devfreq_stats *stats = df->stats;
> +	unsigned int cnt = stats->max_state;
>  
>  	if (cnt == 0)
>  		return count;
>  
>  	mutex_lock(&df->lock);
> -	memset(df->time_in_state, 0, cnt * sizeof(u64));
> -	memset(df->trans_table, 0, cnt * cnt * sizeof(int));
> -	df->last_stat_updated = get_jiffies_64();
> -	df->total_trans = 0;
> +	memset(stats->time_in_state, 0, cnt * sizeof(u64));
> +	memset(stats->trans_table, 0, cnt * cnt * sizeof(int));
> +	stats->last_stat_updated = get_jiffies_64();
> +	stats->total_trans = 0;
>  	mutex_unlock(&df->lock);
>  
>  	return count;
> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
> index b81a86e47fb9..2715719924e7 100644
> --- a/include/linux/devfreq.h
> +++ b/include/linux/devfreq.h
> @@ -106,6 +106,25 @@ struct devfreq_dev_profile {
>  	unsigned int max_state;
>  };
>  
> +/**
> + * struct devfreq_stats - Devfreq's transitions stats counters

Devfreq's transitions stats counters -> Statistics of devfreq device behavior

> + * @freq_table:		List of frequencies in ascending order.
> + * @max_state:		The size of freq_table.
> + * @total_trans:	Number of devfreq transitions.
> + * @trans_table:	Statistics of devfreq transitions.
> + * @time_in_state:	Statistics of devfreq states.
> + * @last_stat_updated:	The last time stats were updated.
> + */
> +struct devfreq_stats {
> +	unsigned long *freq_table;
> +	unsigned int max_state;

Acutally, I'm sorry I has not yet completely agreed to move
'freq_table and 'max_state' from struct devfreq to struct devfreq_stats.
It has not any critical benefit and any problem.
So, don't move 'freq_table' and 'max_state'. 

> +
> +	unsigned int total_trans;
> +	unsigned int *trans_table;
> +	u64 *time_in_state;
> +	unsigned long long last_stat_updated;
> +};
> +
>  /**
>   * struct devfreq - Device devfreq structure
>   * @node:	list node - contains the devices with devfreq that have been
> @@ -131,10 +150,7 @@ struct devfreq_dev_profile {
>   * @suspend_freq:	 frequency of a device set during suspend phase.
>   * @resume_freq:	 frequency of a device set in resume phase.
>   * @suspend_count:	 suspend requests counter for a device.
> - * @total_trans:	Number of devfreq transitions
> - * @trans_table:	Statistics of devfreq transitions
> - * @time_in_state:	Statistics of devfreq states
> - * @last_stat_updated:	The last time stat updated
> + * @stats:	Statistics of devfreq transitions and states times

Statistics of devfreq transitions and states times
-> Statistics of devfreq device behavior

>   * @transition_notifier_list: list head of DEVFREQ_TRANSITION_NOTIFIER notifier
>   *
>   * This structure stores the devfreq information for a give device.
> @@ -171,11 +187,8 @@ struct devfreq {
>  	unsigned long resume_freq;
>  	atomic_t suspend_count;
>  
> -	/* information for device frequency transition */
> -	unsigned int total_trans;
> -	unsigned int *trans_table;
> -	u64 *time_in_state;
> -	unsigned long long last_stat_updated;
> +	/* information for device frequency transitions */
> +	struct devfreq_stats *stats;

Each devfreq has only one stats structure always. Don't need to define
it with pointer type. It is enough to define as following without pointer type:

	struct devfreq_stats stats;

>  
>  	struct srcu_notifier_head transition_notifier_list;
>  };
> 




-- 
Best Regards,
Chanwoo Choi
Samsung Electronics

Re: [PATCH v2 1/3] devfreq: change time stats to 64-bit

[Kamil Konieczny]

Hi,

On 05.12.2019 01:27, Chanwoo Choi wrote:
> On 12/5/19 12:00 AM, Kamil Konieczny wrote:
>> Change time stats counting to bigger type by using 64-bit jiffies.
>> This will make devfreq stats code look similar to cpufreq stats and
>> prevents overflow (for HZ = 1000 after 49.7 days).
>>
>> Signed-off-by: Kamil Konieczny <k.konieczny@samsung.com>
>> Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
>> ---
>> Changes in v2:
>>  added Acked-by, rebased on linux-next
>>
>>  drivers/devfreq/devfreq.c | 14 +++++++-------
>>  include/linux/devfreq.h   |  4 ++--
>>  2 files changed, 9 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>> index bdeb4189c978..0e2030403e4a 100644
>> --- a/drivers/devfreq/devfreq.c
>> +++ b/drivers/devfreq/devfreq.c
>> @@ -199,10 +199,10 @@ static int set_freq_table(struct devfreq *devfreq)
>>  int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>>  {
>>  	int lev, prev_lev, ret = 0;
>> -	unsigned long cur_time;
>> +	unsigned long long cur_time;
> 
> It looks better to use 'u64' instead of 'unsigned long long'.
> Because get_jiffies_u64 has 'u64' return type.

You are right, I will change this and send v3.

>>  
>>  	lockdep_assert_held(&devfreq->lock);
>> -	cur_time = jiffies;
>> +	cur_time = get_jiffies_64();
>>  
>>  	/* Immediately exit if previous_freq is not initialized yet. */
>>  	if (!devfreq->previous_freq)
>> @@ -525,7 +525,7 @@ void devfreq_monitor_resume(struct devfreq *devfreq)
>>  			msecs_to_jiffies(devfreq->profile->polling_ms));
>>  
>>  out_update:
>> -	devfreq->last_stat_updated = jiffies;
>> +	devfreq->last_stat_updated = get_jiffies_64();
>>  	devfreq->stop_polling = false;
>>  
>>  	if (devfreq->profile->get_cur_freq &&
>> @@ -748,7 +748,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
>>  
>>  	devfreq->time_in_state = devm_kcalloc(&devfreq->dev,
>>  			devfreq->profile->max_state,
>> -			sizeof(unsigned long),
>> +			sizeof(*devfreq->time_in_state),
>>  			GFP_KERNEL);
>>  	if (!devfreq->time_in_state) {
>>  		mutex_unlock(&devfreq->lock);
>> @@ -756,7 +756,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
>>  		goto err_devfreq;
>>  	}
>>  
>> -	devfreq->last_stat_updated = jiffies;
>> +	devfreq->last_stat_updated = get_jiffies_64();
>>  
>>  	srcu_init_notifier_head(&devfreq->transition_notifier_list);
>>  
>> @@ -1470,8 +1470,8 @@ static ssize_t trans_stat_show(struct device *dev,
>>  		for (j = 0; j < max_state; j++)
>>  			len += sprintf(buf + len, "%10u",
>>  				devfreq->trans_table[(i * max_state) + j]);
>> -		len += sprintf(buf + len, "%10u\n",
>> -			jiffies_to_msecs(devfreq->time_in_state[i]));
>> +		len += sprintf(buf + len, "%10llu\n", (u64)
>> +			jiffies64_to_msecs(devfreq->time_in_state[i]));
>>  	}
>>  
>>  	len += sprintf(buf + len, "Total transition : %u\n",
>> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
>> index 2bae9ed3c783..b81a86e47fb9 100644
>> --- a/include/linux/devfreq.h
>> +++ b/include/linux/devfreq.h
>> @@ -174,8 +174,8 @@ struct devfreq {
>>  	/* information for device frequency transition */
>>  	unsigned int total_trans;
>>  	unsigned int *trans_table;
>> -	unsigned long *time_in_state;
>> -	unsigned long last_stat_updated;
>> +	u64 *time_in_state;
>> +	unsigned long long last_stat_updated;
> 
> ditto. 'unsigned long long' -> 'u64'.

Yes, will change this too.

>>  	struct srcu_notifier_head transition_notifier_list;
>>  };
>>

-- 
Best regards,
Kamil Konieczny
Samsung R&D Institute Poland

Re: [PATCH v2 2/3] devfreq: add clearing transitions stats

[Kamil Konieczny]

Hi Chanwoo,

On 05.12.2019 01:38, Chanwoo Choi wrote:
> On 12/5/19 12:00 AM, Kamil Konieczny wrote:
>> Add clearing transition table and time in states devfreq statistics
>> by writing to trans_stat file in devfreq sysfs.
> 
> Have to add command example how to reset the trans_stat via sysfs
> on patch description.
> 
> And, have to add how to do it on documentation file as following:
> On next version, please contain the following modification with this patch.
> 
> diff --git a/Documentation/ABI/testing/sysfs-class-devfreq b/Documentation/ABI/testing/sysfs-class-devfreq
> index 75897e2fde43..c172ff838643 100644
> --- a/Documentation/ABI/testing/sysfs-class-devfreq
> +++ b/Documentation/ABI/testing/sysfs-class-devfreq
> @@ -60,7 +60,10 @@ Description:
>                 the number of transitions between states.
>                 In order to activate this ABI, the devfreq target device
>                 driver should provide the list of available frequencies
> -               with its profile.
> +               with its profile. If need to reset the statistics of devfreq
> +               behavior on a specific device, enter 0(zero) to 'trans_stat'
> +               as following:
> +                       echo 0 > /sys/class/devfreq/.../trans_stat
>  
>  What:          /sys/class/devfreq/.../userspace/set_freq
>  Date:          September 2011

Thank you for spotting this and giving patch, I will include it with v3.

>>
>> Signed-off-by: Kamil Konieczny <k.konieczny@samsung.com>
>> ---
>> Changes in v2:
>>  instead of creating new sysfs file, add new functionality to trans_stat
>>  and clear stats when anything is writen to it
>>
>>  drivers/devfreq/devfreq.c | 22 +++++++++++++++++++++-
>>  1 file changed, 21 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>> index 0e2030403e4a..901af3b66a76 100644
>> --- a/drivers/devfreq/devfreq.c
>> +++ b/drivers/devfreq/devfreq.c
>> @@ -1478,7 +1478,27 @@ static ssize_t trans_stat_show(struct device *dev,
>>  					devfreq->total_trans);
>>  	return len;
>>  }
>> -static DEVICE_ATTR_RO(trans_stat);
>> +
>> +static ssize_t trans_stat_store(struct device *dev,
>> +				struct device_attribute *attr,
>> +				const char *buf, size_t count)
>> +{
>> +	struct devfreq *df = to_devfreq(dev);
>> +	unsigned int cnt = df->profile->max_state;
>> +
 
> Why don't you check the input value is whether value is 0(zero) or not?

I will follow your suggestion as this will help to avoid misuse

> If user enter the any value to 'trans_stat', devfreq core
> reset the statistics data. I want to decide the fixed value
> for the reset as following:
> 
> 	echo 0 > /sys/class/devfreq/devfreqX/trans_stat
> 

Thank you, I will add it to commit description.

>> +	if (cnt == 0)
>> +		return count;
>> +
>> +	mutex_lock(&df->lock);
>> +	memset(df->time_in_state, 0, cnt * sizeof(u64));
>> +	memset(df->trans_table, 0, cnt * cnt * sizeof(int));
>> +	df->last_stat_updated = get_jiffies_64();
>> +	df->total_trans = 0;
>> +	mutex_unlock(&df->lock);
>> +
>> +	return count;
>> +}
>> +static DEVICE_ATTR_RW(trans_stat);
>>  
>>  static struct attribute *devfreq_attrs[] = {
>>  	&dev_attr_name.attr,

-- 
Best regards,
Kamil Konieczny
Samsung R&D Institute Poland

Re: [PATCH v2 3/3] devfreq: move statistics to separate struct

[Kamil Konieczny]

Hi,

thank you for review, I will follow you suggestions in v3.

On 05.12.2019 01:28, Matthias Kaehlcke wrote:
> Hi,
> 
> On Wed, Dec 04, 2019 at 04:00:18PM +0100, Kamil Konieczny wrote:
>> Count time and transitions between devfreq frequencies in separate struct
>> for improved code readability and maintenance.
>>
>> Signed-off-by: Kamil Konieczny <k.konieczny@samsung.com>
>> ---
>> Changes in v2:
>>  squash three patches into one, do not modify devfreq_profile and separate stats
>>  into devfreq_stats
>>
>>  drivers/devfreq/devfreq.c | 68 +++++++++++++++++++++++----------------
>>  include/linux/devfreq.h   | 31 ++++++++++++------
>>  2 files changed, 62 insertions(+), 37 deletions(-)
>>
>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>> index 901af3b66a76..4d50c8f10bd2 100644
>> --- a/drivers/devfreq/devfreq.c
>> +++ b/drivers/devfreq/devfreq.c
>> @@ -198,6 +198,7 @@ static int set_freq_table(struct devfreq *devfreq)
>>   */
>>  int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>>  {
>> +	struct devfreq_stats *stats = devfreq->stats;
>>  	int lev, prev_lev, ret = 0;
>>  	unsigned long long cur_time;
>>  
>> @@ -214,8 +215,8 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>>  		goto out;
>>  	}
>>  
>> -	devfreq->time_in_state[prev_lev] +=
>> -			 cur_time - devfreq->last_stat_updated;
>> +	stats->time_in_state[prev_lev] +=
>> +			 cur_time - stats->last_stat_updated;
>>  
>>  	lev = devfreq_get_freq_level(devfreq, freq);
>>  	if (lev < 0) {
>> @@ -224,13 +225,12 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>>  	}
>>  
>>  	if (lev != prev_lev) {
>> -		devfreq->trans_table[(prev_lev *
>> -				devfreq->profile->max_state) + lev]++;
>> -		devfreq->total_trans++;
>> +		stats->trans_table[(prev_lev * stats->max_state) + lev]++;
>> +		stats->total_trans++;
>>  	}
>>  
>>  out:
>> -	devfreq->last_stat_updated = cur_time;
>> +	stats->last_stat_updated = cur_time;
>>  	return ret;
>>  }
>>  EXPORT_SYMBOL(devfreq_update_status);
>> @@ -525,7 +525,7 @@ void devfreq_monitor_resume(struct devfreq *devfreq)
>>  			msecs_to_jiffies(devfreq->profile->polling_ms));
>>  
>>  out_update:
>> -	devfreq->last_stat_updated = get_jiffies_64();
>> +	devfreq->stats->last_stat_updated = get_jiffies_64();
>>  	devfreq->stop_polling = false;
>>  
>>  	if (devfreq->profile->get_cur_freq &&
>> @@ -735,28 +735,38 @@ struct devfreq *devfreq_add_device(struct device *dev,
>>  		goto err_out;
>>  	}
>>  
>> -	devfreq->trans_table = devm_kzalloc(&devfreq->dev,
>> +	devfreq->stats = devm_kzalloc(&devfreq->dev, sizeof(*devfreq->stats),
>> +				      GFP_KERNEL);
>> +	if (!devfreq->stats) {
>> +		mutex_unlock(&devfreq->lock);
>> +		err = -ENOMEM;
>> +		goto err_devfreq;
>> +	}
>> +
>> +	devfreq->stats->freq_table = devfreq->profile->freq_table;
>> +	devfreq->stats->max_state = devfreq->profile->max_state;
>> +	devfreq->stats->trans_table = devm_kzalloc(&devfreq->dev,
>>  			array3_size(sizeof(unsigned int),
>> -				    devfreq->profile->max_state,
>> -				    devfreq->profile->max_state),
>> +				    devfreq->stats->max_state,
>> +				    devfreq->stats->max_state),
>>  			GFP_KERNEL);
>> -	if (!devfreq->trans_table) {
>> +	if (!devfreq->stats->trans_table) {
>>  		mutex_unlock(&devfreq->lock);
>>  		err = -ENOMEM;
>>  		goto err_devfreq;
>>  	}
>>  
>> -	devfreq->time_in_state = devm_kcalloc(&devfreq->dev,
>> -			devfreq->profile->max_state,
>> -			sizeof(*devfreq->time_in_state),
>> +	devfreq->stats->time_in_state = devm_kcalloc(&devfreq->dev,
>> +			devfreq->stats->max_state,
>> +			sizeof(*devfreq->stats->time_in_state),
>>  			GFP_KERNEL);
>> -	if (!devfreq->time_in_state) {
>> +	if (!devfreq->stats->time_in_state) {
>>  		mutex_unlock(&devfreq->lock);
>>  		err = -ENOMEM;
>>  		goto err_devfreq;
>>  	}
>>  
>> -	devfreq->last_stat_updated = get_jiffies_64();
>> +	devfreq->stats->last_stat_updated = get_jiffies_64();
>>  
>>  	srcu_init_notifier_head(&devfreq->transition_notifier_list);
>>  
>> @@ -1435,9 +1445,10 @@ static ssize_t trans_stat_show(struct device *dev,
>>  			       struct device_attribute *attr, char *buf)
>>  {
>>  	struct devfreq *devfreq = to_devfreq(dev);
>> +	struct devfreq_stats *stats = devfreq->stats;
>> +	unsigned int max_state = stats->max_state;
>>  	ssize_t len;
>>  	int i, j;
>> -	unsigned int max_state = devfreq->profile->max_state;
>>  
>>  	if (max_state == 0)
>>  		return sprintf(buf, "Not Supported.\n");
>> @@ -1454,28 +1465,28 @@ static ssize_t trans_stat_show(struct device *dev,
>>  	len += sprintf(buf + len, "           :");
>>  	for (i = 0; i < max_state; i++)
>>  		len += sprintf(buf + len, "%10lu",
>> -				devfreq->profile->freq_table[i]);
>> +				stats->freq_table[i]);
>>  
>>  	len += sprintf(buf + len, "   time(ms)\n");
>>  
>>  	for (i = 0; i < max_state; i++) {
>> -		if (devfreq->profile->freq_table[i]
>> +		if (stats->freq_table[i]
>>  					== devfreq->previous_freq) {
>>  			len += sprintf(buf + len, "*");
>>  		} else {
>>  			len += sprintf(buf + len, " ");
>>  		}
>>  		len += sprintf(buf + len, "%10lu:",
>> -				devfreq->profile->freq_table[i]);
>> +				stats->freq_table[i]);
>>  		for (j = 0; j < max_state; j++)
>>  			len += sprintf(buf + len, "%10u",
>> -				devfreq->trans_table[(i * max_state) + j]);
>> +				stats->trans_table[(i * max_state) + j]);
>>  		len += sprintf(buf + len, "%10llu\n", (u64)
>> -			jiffies64_to_msecs(devfreq->time_in_state[i]));
>> +			jiffies64_to_msecs(stats->time_in_state[i]));
>>  	}
>>  
>>  	len += sprintf(buf + len, "Total transition : %u\n",
>> -					devfreq->total_trans);
>> +					stats->total_trans);
>>  	return len;
>>  }
>>  
>> @@ -1484,16 +1495,17 @@ static ssize_t trans_stat_store(struct device *dev,
>>  				const char *buf, size_t count)
>>  {
>>  	struct devfreq *df = to_devfreq(dev);
>> -	unsigned int cnt = df->profile->max_state;
>> +	struct devfreq_stats *stats = df->stats;
>> +	unsigned int cnt = stats->max_state;
>>  
>>  	if (cnt == 0)
>>  		return count;
>>  
>>  	mutex_lock(&df->lock);
>> -	memset(df->time_in_state, 0, cnt * sizeof(u64));
>> -	memset(df->trans_table, 0, cnt * cnt * sizeof(int));
>> -	df->last_stat_updated = get_jiffies_64();
>> -	df->total_trans = 0;
>> +	memset(stats->time_in_state, 0, cnt * sizeof(u64));
>> +	memset(stats->trans_table, 0, cnt * cnt * sizeof(int));
>> +	stats->last_stat_updated = get_jiffies_64();
>> +	stats->total_trans = 0;
>>  	mutex_unlock(&df->lock);
>>  
>>  	return count;
>> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
>> index b81a86e47fb9..2715719924e7 100644
>> --- a/include/linux/devfreq.h
>> +++ b/include/linux/devfreq.h
>> @@ -106,6 +106,25 @@ struct devfreq_dev_profile {
>>  	unsigned int max_state;
>>  };
>>  
>> +/**
>> + * struct devfreq_stats - Devfreq's transitions stats counters
>> + * @freq_table:		List of frequencies in ascending order.
>> + * @max_state:		The size of freq_table.
>> + * @total_trans:	Number of devfreq transitions.
>> + * @trans_table:	Statistics of devfreq transitions.
>> + * @time_in_state:	Statistics of devfreq states.
>> + * @last_stat_updated:	The last time stats were updated.
>> + */
>> +struct devfreq_stats {
>> +	unsigned long *freq_table;
> 
> nit: trans_stat_show() is the only place where 'freq_table' is
> used. Instead of 'duplicating' it (I know, it's just a pointer)
> you could use a local pointer 'freq_table' in trans_stat_show().
> 
>> +	unsigned int max_state;
> 
> nit: max_state is also a bit of a corner case. It's not really a 'stat' and
> it is already available in struct devfreq_dev_profile, it doesn't seem a
> huge inconvenient to take it from there.

Good hints, I will change this.

>> +
>> +	unsigned int total_trans;
>> +	unsigned int *trans_table;
>> +	u64 *time_in_state;
>> +	unsigned long long last_stat_updated;
> 
> nit: the name 'last_stat_updated' is somewhat redundant, since the
> field is part of a struct called 'devfreq_stats'. 'last_updated' or
> 'last_update' would be concise enough IMO.

This is also good hint.

>> +};
>> +
>>  /**
>>   * struct devfreq - Device devfreq structure
>>   * @node:	list node - contains the devices with devfreq that have been
>> @@ -131,10 +150,7 @@ struct devfreq_dev_profile {
>>   * @suspend_freq:	 frequency of a device set during suspend phase.
>>   * @resume_freq:	 frequency of a device set in resume phase.
>>   * @suspend_count:	 suspend requests counter for a device.
>> - * @total_trans:	Number of devfreq transitions
>> - * @trans_table:	Statistics of devfreq transitions
>> - * @time_in_state:	Statistics of devfreq states
>> - * @last_stat_updated:	The last time stat updated
>> + * @stats:	Statistics of devfreq transitions and states times
>>   * @transition_notifier_list: list head of DEVFREQ_TRANSITION_NOTIFIER notifier
>>   *
>>   * This structure stores the devfreq information for a give device.
>> @@ -171,11 +187,8 @@ struct devfreq {
>>  	unsigned long resume_freq;
>>  	atomic_t suspend_count;
>>  
>> -	/* information for device frequency transition */
>> -	unsigned int total_trans;
>> -	unsigned int *trans_table;
>> -	u64 *time_in_state;
>> -	unsigned long long last_stat_updated;
>> +	/* information for device frequency transitions */
>> +	struct devfreq_stats *stats;
>>  
>>  	struct srcu_notifier_head transition_notifier_list;
>>  };
> 
> My comments above are just suggestions:
> 
> Reviewed-by: Matthias Kaehlcke <mka@chromium.org>

-- 
Best regards,
Kamil Konieczny
Samsung R&D Institute Poland

Re: [PATCH v2 3/3] devfreq: move statistics to separate struct

[Kamil Konieczny]

Hi Chanwoo,

On 05.12.2019 02:46, Chanwoo Choi wrote:
> On 12/5/19 12:00 AM, Kamil Konieczny wrote:
>> Count time and transitions between devfreq frequencies in separate struct
>> for improved code readability and maintenance.
>>
>> Signed-off-by: Kamil Konieczny <k.konieczny@samsung.com>
>> ---
>> Changes in v2:
>>  squash three patches into one, do not modify devfreq_profile and separate stats
>>  into devfreq_stats
>>
>>  drivers/devfreq/devfreq.c | 68 +++++++++++++++++++++++----------------
>>  include/linux/devfreq.h   | 31 ++++++++++++------
>>  2 files changed, 62 insertions(+), 37 deletions(-)
>>
>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>> index 901af3b66a76..4d50c8f10bd2 100644
>> --- a/drivers/devfreq/devfreq.c
>> +++ b/drivers/devfreq/devfreq.c
>> @@ -198,6 +198,7 @@ static int set_freq_table(struct devfreq *devfreq)
>>   */
>>  int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>>  {
>> +	struct devfreq_stats *stats = devfreq->stats;
>>  	int lev, prev_lev, ret = 0;
>>  	unsigned long long cur_time;
>>  
>> @@ -214,8 +215,8 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>>  		goto out;
>>  	}
>>  
>> -	devfreq->time_in_state[prev_lev] +=
>> -			 cur_time - devfreq->last_stat_updated;
>> +	stats->time_in_state[prev_lev] +=
>> +			 cur_time - stats->last_stat_updated;
>>  
>>  	lev = devfreq_get_freq_level(devfreq, freq);
>>  	if (lev < 0) {
>> @@ -224,13 +225,12 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
>>  	}
>>  
>>  	if (lev != prev_lev) {
>> -		devfreq->trans_table[(prev_lev *
>> -				devfreq->profile->max_state) + lev]++;
>> -		devfreq->total_trans++;
>> +		stats->trans_table[(prev_lev * stats->max_state) + lev]++;
>> +		stats->total_trans++;
>>  	}
>>  
>>  out:
>> -	devfreq->last_stat_updated = cur_time;
>> +	stats->last_stat_updated = cur_time;
>>  	return ret;
>>  }
>>  EXPORT_SYMBOL(devfreq_update_status);
>> @@ -525,7 +525,7 @@ void devfreq_monitor_resume(struct devfreq *devfreq)
>>  			msecs_to_jiffies(devfreq->profile->polling_ms));
>>  
>>  out_update:
>> -	devfreq->last_stat_updated = get_jiffies_64();
>> +	devfreq->stats->last_stat_updated = get_jiffies_64();
>>  	devfreq->stop_polling = false;
>>  
>>  	if (devfreq->profile->get_cur_freq &&
>> @@ -735,28 +735,38 @@ struct devfreq *devfreq_add_device(struct device *dev,
>>  		goto err_out;
>>  	}
>>  
>> -	devfreq->trans_table = devm_kzalloc(&devfreq->dev,
>> +	devfreq->stats = devm_kzalloc(&devfreq->dev, sizeof(*devfreq->stats),
>> +				      GFP_KERNEL);
> 
> Each devfreq has only one stats structure always. Don't need to define
> it with pointer type. It is enough to define as following without pointer type:
> 
> 	struct devfreq_stats stats;
> 
Good point, I will change this.

>> +	if (!devfreq->stats) {
>> +		mutex_unlock(&devfreq->lock);
>> +		err = -ENOMEM;
>> +		goto err_devfreq;
>> +	}
>> +
>> +	devfreq->stats->freq_table = devfreq->profile->freq_table;
>> +	devfreq->stats->max_state = devfreq->profile->max_state;
>> +	devfreq->stats->trans_table = devm_kzalloc(&devfreq->dev,
>>  			array3_size(sizeof(unsigned int),
>> -				    devfreq->profile->max_state,
>> -				    devfreq->profile->max_state),
>> +				    devfreq->stats->max_state,
>> +				    devfreq->stats->max_state),
>>  			GFP_KERNEL);
>> -	if (!devfreq->trans_table) {
>> +	if (!devfreq->stats->trans_table) {
>>  		mutex_unlock(&devfreq->lock);
>>  		err = -ENOMEM;
>>  		goto err_devfreq;
>>  	}
>>  
>> -	devfreq->time_in_state = devm_kcalloc(&devfreq->dev,
>> -			devfreq->profile->max_state,
>> -			sizeof(*devfreq->time_in_state),
>> +	devfreq->stats->time_in_state = devm_kcalloc(&devfreq->dev,
>> +			devfreq->stats->max_state,
>> +			sizeof(*devfreq->stats->time_in_state),
>>  			GFP_KERNEL);
> 
> Actually, this patch will be conflict with patch[1].
> [1] https://www.spinics.net/lists/arm-kernel/msg768822.html
> 
> First of all, I have to merge patches[1][2] for the devfreq pm-qos
> during v5.5-rc period. It requires the linux-pm's maintainer.
> [2] https://www.spinics.net/lists/arm-kernel/msg769761.html
> 
> After finishing the job[1][2], I'll merge this patch
> if finished the review of this patch. Just share the possible merge
> conflict to you.
> 

Ok, I will rebase and send when you will need this,
please remind me when it happens.

> 
>> -	if (!devfreq->time_in_state) {
>> +	if (!devfreq->stats->time_in_state) {
>>  		mutex_unlock(&devfreq->lock);
>>  		err = -ENOMEM;
>>  		goto err_devfreq;
>>  	}
>>  
>> -	devfreq->last_stat_updated = get_jiffies_64();
>> +	devfreq->stats->last_stat_updated = get_jiffies_64();
>>  
>>  	srcu_init_notifier_head(&devfreq->transition_notifier_list);
>>  
>> @@ -1435,9 +1445,10 @@ static ssize_t trans_stat_show(struct device *dev,
>>  			       struct device_attribute *attr, char *buf)
>>  {
>>  	struct devfreq *devfreq = to_devfreq(dev);
>> +	struct devfreq_stats *stats = devfreq->stats;
>> +	unsigned int max_state = stats->max_state;
>>  	ssize_t len;
>>  	int i, j;
>> -	unsigned int max_state = devfreq->profile->max_state;
>>  
>>  	if (max_state == 0)
>>  		return sprintf(buf, "Not Supported.\n");
>> @@ -1454,28 +1465,28 @@ static ssize_t trans_stat_show(struct device *dev,
>>  	len += sprintf(buf + len, "           :");
>>  	for (i = 0; i < max_state; i++)
>>  		len += sprintf(buf + len, "%10lu",
>> -				devfreq->profile->freq_table[i]);
>> +				stats->freq_table[i]);
>>  
>>  	len += sprintf(buf + len, "   time(ms)\n");
>>  
>>  	for (i = 0; i < max_state; i++) {
>> -		if (devfreq->profile->freq_table[i]
>> +		if (stats->freq_table[i]
>>  					== devfreq->previous_freq) {
>>  			len += sprintf(buf + len, "*");
>>  		} else {
>>  			len += sprintf(buf + len, " ");
>>  		}
>>  		len += sprintf(buf + len, "%10lu:",
>> -				devfreq->profile->freq_table[i]);
>> +				stats->freq_table[i]);
>>  		for (j = 0; j < max_state; j++)
>>  			len += sprintf(buf + len, "%10u",
>> -				devfreq->trans_table[(i * max_state) + j]);
>> +				stats->trans_table[(i * max_state) + j]);
>>  		len += sprintf(buf + len, "%10llu\n", (u64)
>> -			jiffies64_to_msecs(devfreq->time_in_state[i]));
>> +			jiffies64_to_msecs(stats->time_in_state[i]));
>>  	}
>>  
>>  	len += sprintf(buf + len, "Total transition : %u\n",
>> -					devfreq->total_trans);
>> +					stats->total_trans);
>>  	return len;
>>  }
>>  
>> @@ -1484,16 +1495,17 @@ static ssize_t trans_stat_store(struct device *dev,
>>  				const char *buf, size_t count)
>>  {
>>  	struct devfreq *df = to_devfreq(dev);
>> -	unsigned int cnt = df->profile->max_state;
>> +	struct devfreq_stats *stats = df->stats;
>> +	unsigned int cnt = stats->max_state;
>>  
>>  	if (cnt == 0)
>>  		return count;
>>  
>>  	mutex_lock(&df->lock);
>> -	memset(df->time_in_state, 0, cnt * sizeof(u64));
>> -	memset(df->trans_table, 0, cnt * cnt * sizeof(int));
>> -	df->last_stat_updated = get_jiffies_64();
>> -	df->total_trans = 0;
>> +	memset(stats->time_in_state, 0, cnt * sizeof(u64));
>> +	memset(stats->trans_table, 0, cnt * cnt * sizeof(int));
>> +	stats->last_stat_updated = get_jiffies_64();
>> +	stats->total_trans = 0;
>>  	mutex_unlock(&df->lock);
>>  
>>  	return count;
>> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
>> index b81a86e47fb9..2715719924e7 100644
>> --- a/include/linux/devfreq.h
>> +++ b/include/linux/devfreq.h
>> @@ -106,6 +106,25 @@ struct devfreq_dev_profile {
>>  	unsigned int max_state;
>>  };
>>  
>> +/**
>> + * struct devfreq_stats - Devfreq's transitions stats counters
> 
> Devfreq's transitions stats counters -> Statistics of devfreq device behavior

Thanks, changed.

>> + * @freq_table:		List of frequencies in ascending order.
>> + * @max_state:		The size of freq_table.
>> + * @total_trans:	Number of devfreq transitions.
>> + * @trans_table:	Statistics of devfreq transitions.
>> + * @time_in_state:	Statistics of devfreq states.
>> + * @last_stat_updated:	The last time stats were updated.
>> + */
>> +struct devfreq_stats {
>> +	unsigned long *freq_table;
>> +	unsigned int max_state;
> 
> Acutally, I'm sorry I has not yet completely agreed to move
> 'freq_table and 'max_state' from struct devfreq to struct devfreq_stats.
> It has not any critical benefit and any problem.
> So, don't move 'freq_table' and 'max_state'. 

I removed these two from devfreq_stats and use devfreq->profile as in original
devfreq code.

> 
>> +
>> +	unsigned int total_trans;
>> +	unsigned int *trans_table;
>> +	u64 *time_in_state;
>> +	unsigned long long last_stat_updated;
>> +};
>> +
>>  /**
>>   * struct devfreq - Device devfreq structure
>>   * @node:	list node - contains the devices with devfreq that have been
>> @@ -131,10 +150,7 @@ struct devfreq_dev_profile {
>>   * @suspend_freq:	 frequency of a device set during suspend phase.
>>   * @resume_freq:	 frequency of a device set in resume phase.
>>   * @suspend_count:	 suspend requests counter for a device.
>> - * @total_trans:	Number of devfreq transitions
>> - * @trans_table:	Statistics of devfreq transitions
>> - * @time_in_state:	Statistics of devfreq states
>> - * @last_stat_updated:	The last time stat updated
>> + * @stats:	Statistics of devfreq transitions and states times
> 
> Statistics of devfreq transitions and states times
> -> Statistics of devfreq device behavior
>

Ok.
 
>>   * @transition_notifier_list: list head of DEVFREQ_TRANSITION_NOTIFIER notifier
>>   *
>>   * This structure stores the devfreq information for a give device.
>> @@ -171,11 +187,8 @@ struct devfreq {
>>  	unsigned long resume_freq;
>>  	atomic_t suspend_count;
>>  
>> -	/* information for device frequency transition */
>> -	unsigned int total_trans;
>> -	unsigned int *trans_table;
>> -	u64 *time_in_state;
>> -	unsigned long long last_stat_updated;
>> +	/* information for device frequency transitions */
>> +	struct devfreq_stats *stats;
> 
> Each devfreq has only one stats structure always. Don't need to define
> it with pointer type. It is enough to define as following without pointer type:
> 
> 	struct devfreq_stats stats;
> 
>>  
>>  	struct srcu_notifier_head transition_notifier_list;
>>  };
>>
-- 
Best regards,
Kamil Konieczny
Samsung R&D Institute Poland