Re: eventdev: method for finding out unlink status
From: Elo, Matias (Nokia - FI/Espoo) <hidden>
Date: 2018-08-08 10:05:06
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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?