[dpdk-dev] eventdev: method for finding out unlink status
Elo, Matias (Nokia - FI/Espoo)
matias.elo at nokia.com
Wed Aug 8 12:05:05 CEST 2018
>>>>>>>
>>>>>>> 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?
>>
>> Based on return code?
>
> Yes, that works. I was thinking about the complexity of the implementation as it would
> have to also track the pending unlink requests. But anyway, Harry is better answering
> these questions since I guess he would be implementing this.
Hi Harry,
Have you had time to think about this?
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