Hi,

Thanks for the reply! I've also emailed the ath10k and linux-wireless list and waiting to hear back suggestions.

In the meantime can you educate me how the aqm queue interacts with wifi driver? Is that the driver pulls from the queue from time to time, instead of aqm pushes to the network interface? How often or what triggers the driver to pull?

I hope I can verify that if you can point me to the code to check that :)

And, for the queue itself, how long it's supposed to drop packets and clean up? It seems that when it's full, it notifies back-pressure to the socket instead of simply dropping the packets from the head or the tail of the queue?

Many thanks!

Joshua

On Fri, Apr 12, 2019 at 2:18 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:

Joshua Zhao <swzhao@gmail.com> writes:

> Hi,
> I run into a weird symptom that occasionally the aqm tx queue can get stuck
> for quite long time (maybe around 30min). What happened is that we're
> sending a low bandwidth UDP traffic from the host to multiple peers over a
> WiFi radio simultaneously. We're running opensource mac80211 + ath10k
> driver. Very occasionally when there are temporary issues causing trouble
> on the host sending to one of the peers, the queue to all peers can get
> stuck and stay stuck for quite long (even though the link trouble had been
> gone or TX had been stopped). Only after quite a while, then the queue
> cleans up.

This sorta sounds like a driver bug where the queue doesn't get
restarted after the issue is resolved? I'd suggest you email the ath10k
(ath10k@lists.infradead.org - maybe cc linux-wireless@vger.kernel.org
and this list) with a description of the issue that triggers this bug,
as well as system details (hardware model, firmware version and kernel
version).

-Toke