doubt on schedule_work() - work task getting scheduled lately

[Daniel.]

Nice tool @Ricardo!

2016-07-29 10:48 GMT-03:00 Ricardo Ribalda Delgado <ricardo.ribalda at gmail.com>:
> you can use http://lttng.org/ for analyzing this
>
> Regards!
>
> On Fri, Jul 29, 2016 at 12:44 PM, Pranay Srivastava <pranjas at gmail.com> wrote:
>> On Fri, Jul 29, 2016 at 4:02 PM, Muni Sekhar <munisekharrms at gmail.com> wrote:
>>> Hi All,
>>>
>>> I have a doubt regarding the workqueue scheduling.
>>>
>>> I am using the workqueue for processing the Rx Interrupt data. I am
>>> calling schedule_work() on receiving the Rx interrupt from hardware.
>>>
>>> I calculated the time between calling the schedule_work() and
>>> workqueue task actually getting executed, Here I see many cases of
>>> less than 100 us(It is fairly good).
>>>
>>> But sometimes I see 10’s of ms and a lot in the 100’s of ms. I have
>>> seen over 0.5 secs too. I would like to know why does sometimes kernel
>>> takes longer time(in milli seconds) to schedule it? Is there any way
>>> to reduce this time gap?
>>>
>>>
>>> My code:
>>>
>>> static void my_workqueuetask(struct work_struct *work)
>>> {
>>>     printk("In %s() \n",__func__);
>>>
>> You probably don't need this if it's just for your work_fn, yeah but
>> if there's race between this and something else...
>>>     mutex_lock(&bh_mutex);
>>>
>>>     //Do something here
>>>
>>>     mutex_unlock(&bh_mutex);
>>> }
>>>
>>>
>>> static irqreturn_t my_irq_handler(int irq, void *dev)
>>> {
>>>         ……;
>>>
>>>         if(Rx Interrupt)
>>>              schedule_work(&rx_work);
>>
>> Maybe system_wq has too much already on it's plate?
>> Have you tried the same with completion and a kthread? or
>> with your own workqueue, overkill but you can give it a shot.
>>>
>>> return IRQ_HANDLED;
>>> }
>>>
>>> --
>>> Thanks,
>>> Sekhar
>>>
>>> _______________________________________________
>>> Kernelnewbies mailing list
>>> Kernelnewbies at kernelnewbies.org
>>> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>>
>>
>>
>> --
>>         ---P.K.S
>>
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>
>
>
> --
> Ricardo Ribalda
>
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> Kernelnewbies at kernelnewbies.org
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