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

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