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

Chanwoo Choi
2019-12-05T00:32:03Z

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