>>>>
>>>> I think the end result we're hoping for is something like pseudo code
>>>> below,
>>>> (keep in mind that the event/sw has a service-core thread running it, so no
>>>> application code there):
>>>>
>>>> int worker_poll = 1;
>>>>
>>>> worker() {
>>>> while(worker_poll) {
>>>> // eventdev_dequeue_burst() etc
>>>> }
>>>> go_to_sleep(1);
>>>> }
>>>>
>>>> control_plane_scale_down() {
>>>> unlink(evdev, worker, queue_id);
>>>> while(unlinks_in_progress(evdev) > 0)
>>>> usleep(100);
>>>>
>>>> /* here we know that the unlink is complete.
>>>> * so we can now stop the worker from polling */
>>>> worker_poll = 0;
>>>> }
>>>
>>>
>>> Make sense. Instead of rte_event_is_unlink_in_progress(), How about
>>> adding a callback in rte_event_port_unlink() which will be called on
>>> unlink completion. It will reduce the need for ONE more API.
>>>
>>> Anyway it RC2 now, so we can not accept a new feature. So we will have
>>> time for deprecation notice.
>>>
>>
>> Both solutions should work but I would perhaps favor Harry's approach as it
>> requires less code in the application side and doesn't break backward
>> compatibility.
>
> OK.
>
> Does rte_event_port_unlink() returning -EBUSY will help?
It could perhaps work. The return value becomes a bit ambiguous though. E.g. how
to differentiate a delayed unlink completion from a scenario where the port &
queues
have never been linked?
The implementation may also be more complex compared to a separate function but
Harry is a better person to answer this.
>
> while (rte_event_port_unlink() != nr_links)
> usleep(100);
>
> I am trying to think, how can address this requirements without creating new
> API and/or less impact to other
> drivers which don't have this requirements?
Wouldn't this function then just be NOP for the other drivers?
>
> Are we calling this API in fastpath? or it is control thread as
> mentioned in harry's pseudo code.
In our use case it could be called also directly from the fast path by the
worker thread.
