Messages in this thread | | | Subject | Re: [PATCH 2/4] PM / devfreq: add possibility for delayed work | From | Kamil Konieczny <> | Date | Tue, 10 Dec 2019 10:03:27 +0100 |
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Hi Chanwoo,
On 10.12.2019 02:47, Chanwoo Choi wrote: > On 12/9/19 11:44 PM, Kamil Konieczny wrote: >> Current devfreq workqueue uses deferred timer. Introduce sysfs >> file delayed_timer and use it for change from deferred to >> delayed work. The default is to use old deferred one, which >> saves power, but can miss increased demand for higher bus >> frequency if timer was assigned to idle cpu. > > As I commented on patch1, If you hope to change the feature > related to both performance and power-consumption, > you have to suggest the reasonable data with test result > on multiple scenarios.
Unfortunatly I do not have such tests. Do you have them ? May you share them with me or Marek ?
> Firstly, > I don't agree to add 'delayed_timer' sysfs entries. > If some device driver want to use the different type of > workqueue, they can choice the workqueue type in the > probe function of device driver.
sysfs allows change in runtime
> Secondly, the 'dealyed_timer' is not for all devfreq > device driver. Only devfreq device driver uses the > 'simple_ondemand' governor. It is wrong to show > without any specific reason.
Good point, performance or powersave with fixed max or min freq do not need them.
> If you suggest the reasonable data with test result, > I prefer to add the new flag to 'struct devfreq_dev_profile'.
imho users of devfreq may give it a try and perform tests themselfs and then share results.
>> >> Signed-off-by: Kamil Konieczny <k.konieczny@samsung.com> >> --- >> Documentation/ABI/testing/sysfs-class-devfreq | 10 ++++ >> drivers/devfreq/devfreq.c | 46 ++++++++++++++++++- >> include/linux/devfreq.h | 2 + >> 3 files changed, 57 insertions(+), 1 deletion(-) >> >> diff --git a/Documentation/ABI/testing/sysfs-class-devfreq b/Documentation/ABI/testing/sysfs-class-devfreq >> index 9758eb85ade3..07bfd0df6a4a 100644 >> --- a/Documentation/ABI/testing/sysfs-class-devfreq >> +++ b/Documentation/ABI/testing/sysfs-class-devfreq >> @@ -30,6 +30,16 @@ Description: >> target_freq when get_cur_freq() is not implemented by >> devfreq driver. >> >> +What: /sys/class/devfreq/.../delayed_timer >> +Date: December 2019 >> +Contact: Kamil Konieczny <k.konieczny@samsung.com> >> +Description: >> + This ABI shows or clears timer type used by devfreq >> + workqueue. When 0, it uses default deferred timer. >> + When set to 1 devfreq will use delayed timer. Example >> + useage: >> + echo 1 > /sys/class/devfreq/.../delayed_timer >> + >> What: /sys/class/devfreq/.../target_freq >> Date: September 2012 >> Contact: Rajagopal Venkat <rajagopal.venkat@linaro.org> >> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c >> index 955949c6fc1f..c277d1770fef 100644 >> --- a/drivers/devfreq/devfreq.c >> +++ b/drivers/devfreq/devfreq.c >> @@ -445,7 +445,11 @@ void devfreq_monitor_start(struct devfreq *devfreq) >> if (devfreq->governor->interrupt_driven) >> return; >> >> - INIT_DEFERRABLE_WORK(&devfreq->work, devfreq_monitor); >> + if (devfreq->delayed_timer) >> + INIT_DELAYED_WORK(&devfreq->work, devfreq_monitor); >> + else >> + INIT_DEFERRABLE_WORK(&devfreq->work, devfreq_monitor); >> + >> if (devfreq->profile->polling_ms) >> queue_delayed_work(devfreq_wq, &devfreq->work, >> msecs_to_jiffies(devfreq->profile->polling_ms)); >> @@ -698,6 +702,7 @@ struct devfreq *devfreq_add_device(struct device *dev, >> devfreq->last_status.current_frequency = profile->initial_freq; >> devfreq->data = data; >> devfreq->nb.notifier_call = devfreq_notifier_call; >> + devfreq->delayed_timer = false; >> >> if (!devfreq->profile->max_state && !devfreq->profile->freq_table) { >> mutex_unlock(&devfreq->lock); >> @@ -1288,6 +1293,44 @@ static ssize_t available_governors_show(struct device *d, >> } >> static DEVICE_ATTR_RO(available_governors); >> >> +static ssize_t delayed_timer_show(struct device *dev, >> + struct device_attribute *attr, char *buf) >> +{ >> + int i; >> + >> + i = to_devfreq(dev)->delayed_timer ? 1 : 0; >> + return sprintf(buf, "%d\n", i); >> +} >> + >> +static ssize_t delayed_timer_store(struct device *dev, >> + struct device_attribute *attr, >> + const char *buf, size_t count) >> +{ >> + struct devfreq *df = to_devfreq(dev); >> + bool old_timer; >> + int value, ret; >> + >> + if (!df->governor) >> + return -EINVAL; >> + >> + ret = kstrtoint(buf, 10, &value); >> + if (ret || (value != 1 && value != 0)) >> + return -EINVAL; >> + >> + mutex_lock(&df->lock); >> + old_timer = df->delayed_timer; >> + df->delayed_timer = value == 0 ? false : true; >> + mutex_unlock(&df->lock); >> + >> + if (old_timer != df->delayed_timer) { >> + devfreq_monitor_stop(df); >> + devfreq_monitor_start(df); >> + } >> + >> + return count; >> +} >> +static DEVICE_ATTR_RW(delayed_timer); >> + >> static ssize_t cur_freq_show(struct device *dev, struct device_attribute *attr, >> char *buf) >> { >> @@ -1513,6 +1556,7 @@ static struct attribute *devfreq_attrs[] = { >> &dev_attr_name.attr, >> &dev_attr_governor.attr, >> &dev_attr_available_governors.attr, >> + &dev_attr_delayed_timer.attr, >> &dev_attr_cur_freq.attr, >> &dev_attr_available_frequencies.attr, >> &dev_attr_target_freq.attr, >> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h >> index de2fdc56aa5b..761aa0a09db7 100644 >> --- a/include/linux/devfreq.h >> +++ b/include/linux/devfreq.h >> @@ -134,6 +134,7 @@ struct devfreq_stats { >> * reevaluate operable frequencies. Devfreq users may use >> * devfreq.nb to the corresponding register notifier call chain. >> * @work: delayed work for load monitoring. >> + * @delayed_timer: use delayed or deferred timer for workqueue. >> * @previous_freq: previously configured frequency value. >> * @data: Private data of the governor. The devfreq framework does not >> * touch this. >> @@ -166,6 +167,7 @@ struct devfreq { >> char governor_name[DEVFREQ_NAME_LEN]; >> struct notifier_block nb; >> struct delayed_work work; >> + bool delayed_timer; >> >> unsigned long previous_freq; >> struct devfreq_dev_status last_status; >> > >
-- Best regards, Kamil Konieczny Samsung R&D Institute Poland
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