Re: [PATCH v3 3/3] devfreq: move statistics to separate struct

From: Chanwoo Choi
Date: Fri Dec 06 2019 - 00:24:19 EST


Hi,

Looks good. But, it include the some clean-up code
regardless of 'struct stats'. So, I modified them as following by myself:

- Remove the code touched the 'devfreq->profile' in this patch
- Use 'devfreq->stats.*' style instead of 'stats->*' in order to
keep the consistent coding style.

On 12/5/19 11:55 PM, 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@xxxxxxxxxxx>
> Reviewed-by: Matthias Kaehlcke <mka@xxxxxxxxxxxx>
> ---
> Changes in v3:
> - removed freq_table and max_state from struct devfreq_stats as they are
> already present in struct devfreq_dev_profile
> - renamed last_stat_updated to last_update, as 'stat' is already present
> in struct devfreq_stats
> - define struct devfreq_stats stats; in devfreq as there is only one
> stats per devfreq
> - improve descriptions of devfreq_stats and stats
> - use profile instead of devfreq->profile in devfreq_add_device, as this
> var is already parameter
> - added Reviewed-by: Matthias Kaehlcke <mka@xxxxxxxxxxxx>
>
> Changes in v2:
> - squash three patches into one, do not modify devfreq_profile and separate stats
> into devfreq_stats
> ---
> drivers/devfreq/devfreq.c | 67 ++++++++++++++++++++-------------------
> include/linux/devfreq.h | 26 +++++++++------
> 2 files changed, 51 insertions(+), 42 deletions(-)
>
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 218eb64d7f28..bcd7e92d2cf3 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;
> u64 cur_time;
>
> @@ -214,9 +215,7 @@ 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_update;
> lev = devfreq_get_freq_level(devfreq, freq);
> if (lev < 0) {
> ret = lev;
> @@ -224,13 +223,13 @@ 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 * devfreq->profile->max_state) +
> + lev]++;
> + stats->total_trans++;
> }
>
> out:
> - devfreq->last_stat_updated = cur_time;
> + stats->last_update = cur_time;
> return ret;
> }
> EXPORT_SYMBOL(devfreq_update_status);
> @@ -525,7 +524,7 @@ 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_update = get_jiffies_64();
> devfreq->stop_polling = false;
>
> if (devfreq->profile->get_cur_freq &&
> @@ -735,28 +734,29 @@ struct devfreq *devfreq_add_device(struct device *dev,
> goto err_out;
> }
>
> - devfreq->trans_table = devm_kzalloc(&devfreq->dev,
> + devfreq->stats.trans_table = devm_kzalloc(&devfreq->dev,
> array3_size(sizeof(unsigned int),
> - devfreq->profile->max_state,
> - devfreq->profile->max_state),

It is not good touching the 'devfreq->profile' variable
that is not related to 'struct devfreq_stats'. Just keep the previous code.


> + profile->max_state,
> + profile->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,
> + profile->max_state,

ditto. Just keep the previous code.

> + 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_update = get_jiffies_64();
> + devfreq->stats.total_trans = 0;
>
> srcu_init_notifier_head(&devfreq->transition_notifier_list);
>
> @@ -1435,9 +1435,11 @@ 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 = devfreq->profile->max_state;
> + unsigned long *freq_table = devfreq->profile->freq_table;
> ssize_t len;
> int i, j;
> - unsigned int max_state = devfreq->profile->max_state;

It is not good touching the 'devfreq->profile' variable
that is not related to 'struct devfreq_stats'.

>
> if (max_state == 0)
> return sprintf(buf, "Not Supported.\n");
> @@ -1453,29 +1455,27 @@ static ssize_t trans_stat_show(struct device *dev,
> len = sprintf(buf, " From : To\n");
> len += sprintf(buf + len, " :");
> for (i = 0; i < max_state; i++)
> - len += sprintf(buf + len, "%10lu",
> - devfreq->profile->freq_table[i]);
> + len += sprintf(buf + len, "%10lu", freq_table[i]);

It is not good touching the 'devfreq->profile' variable
that is not related to 'struct devfreq_stats'.

>
> len += sprintf(buf + len, " time(ms)\n");
>
> for (i = 0; i < max_state; i++) {
> - if (devfreq->profile->freq_table[i]
> - == devfreq->previous_freq) {
> + if (freq_table[i] == devfreq->previous_freq)

ditto.

> len += sprintf(buf + len, "*");
> - } else {

Don't touch the something if it is not related to 'struct devfreq_stats'

> + else
> len += sprintf(buf + len, " ");
> - }

ditto.

> - len += sprintf(buf + len, "%10lu:",
> - devfreq->profile->freq_table[i]);
> +
> + len += sprintf(buf + len, "%10lu:", freq_table[i]);

ditto.

> 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;
> }
>
> @@ -1484,6 +1484,7 @@ static ssize_t trans_stat_store(struct device *dev,
> const char *buf, size_t count)
> {
> struct devfreq *df = to_devfreq(dev);
> + struct devfreq_stats *stats = &df->stats;
> unsigned int cnt = df->profile->max_state;
> int err, value;
>
> @@ -1495,10 +1496,10 @@ static ssize_t trans_stat_store(struct device *dev,
> 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_update = 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 41f15e7a22b8..de2fdc56aa5b 100644
> --- a/include/linux/devfreq.h
> +++ b/include/linux/devfreq.h
> @@ -106,6 +106,20 @@ struct devfreq_dev_profile {
> unsigned int max_state;
> };
>
> +/**
> + * struct devfreq_stats - Statistics of devfreq device behavior
> + * @total_trans: Number of devfreq transitions.
> + * @trans_table: Statistics of devfreq transitions.
> + * @time_in_state: Statistics of devfreq states.
> + * @last_update: The last time stats were updated.
> + */
> +struct devfreq_stats {
> + unsigned int total_trans;
> + unsigned int *trans_table;
> + u64 *time_in_state;
> + u64 last_update;
> +};
> +
> /**
> * struct devfreq - Device devfreq structure
> * @node: list node - contains the devices with devfreq that have been
> @@ -131,10 +145,7 @@ 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 device behavior
> * @transition_notifier_list: list head of DEVFREQ_TRANSITION_NOTIFIER notifier
> *
> * This structure stores the devfreq information for a give device.
> @@ -171,11 +182,8 @@ 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;
> - u64 last_stat_updated;
> + /* information for device frequency transitions */
> + struct devfreq_stats stats;
>
> struct srcu_notifier_head transition_notifier_list;
> };
>


--
Best Regards,
Chanwoo Choi
Samsung Electronics