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

Chanwoo Choi
2019-12-05T00:21:11Z

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