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SubjectRe: [PATCH v2 2/2] drivers: devfreq: change deferred work into delayed
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Hi Matthias,

On 2/11/19 10:36 PM, Matthias Kaehlcke wrote:
> Hi Lukasz,
>
> On Mon, Feb 11, 2019 at 04:30:05PM +0100, Lukasz Luba wrote:
>> This patch changes deferred work to delayed work, which is now not missed
>> when timer is put on CPU that entered idle state.
>> The devfreq framework governor was not called, thus changing the device's
>> frequency did not happen.
>> Benchmarks for stressing Dynamic Memory Controller show x2 (in edge cases
>> even x5) performance boost with this patch when 'simpleondemand_governor'
>> is responsible for monitoring the device load and frequency changes.
>>
>> With this patch, the delayed work is done no mater CPUs' idle.
>> All of the drivers in devfreq which rely on periodic, guaranteed wakeup
>> intervals should benefit from it.
>>
>> Signed-off-by: Lukasz Luba <l.luba@partner.samsung.com>
>> ---
>> drivers/devfreq/devfreq.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>> index 882e717..c200b3c 100644
>> --- a/drivers/devfreq/devfreq.c
>> +++ b/drivers/devfreq/devfreq.c
>> @@ -400,7 +400,7 @@ static void devfreq_monitor(struct work_struct *work)
>> */
>> void devfreq_monitor_start(struct devfreq *devfreq)
>> {
>> - INIT_DEFERRABLE_WORK(&devfreq->work, devfreq_monitor);
>> + INIT_DELAYED_WORK(&devfreq->work, devfreq_monitor);
>> if (devfreq->profile->polling_ms)
>> schedule_delayed_work(&devfreq->work,
>> msecs_to_jiffies(devfreq->profile->polling_ms));
>
> I'd suggest to swap the order of the patches in this series.
>
> Why, you may ask, if the end product is the same? This patch ([2/2])
> fixes an actual problem, while IIUC [1/2] is just an improvement, the
> fix doesn't really depend on it. If -stable wants to integrate the
> fix, they also need to pick the improvement (or resolve a conflict),
> which might not be desired.
Good point, I will reorder them.
>
> Otherwise this looks sane to me:
>
> Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
>
>
Thank you for the review.

Regards,
Lukasz

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