Rajkumar Manoharan [off-list ref] writes:

quoted

quoted

As mentioned earlier, next_txq() can not be used for fetching txq
directly. So reorder_txq() needs to take care of refilling txq after
serving them.

Yeah, I got that; but see above. Unless there's a guarantee that the
push/pull mechanism will be round-robin scheduled (which as I'm reading
the code there isn't), just increasing the deficit on every call to
reorder_txq() is not going to ensure fairness (it'll probably help 
some,
but it won't be completely fair).

However, if we add the check to reorder_txq() so the deficit increase +
rotation is only done if the TXQ is at the head of the list, we'll get
round-robin-equivalent behaviour since a TXQ will only get to continue
when it happens to have rotated to the head of the queue. As I 
mentioned
previously it will break MIMO, but I we could fix that later once we've
verified that the basic mechanism works.

Hmm... The pull mechanism operates in round-robin fashion. Agree that
accessing only head node is right way of ensuring fairness.

Ah, excellent; then it should be no problem to enforce the head node
access; worst case the pull mechanism will be at a different point in
the round-robin, which will sync up quickly.

Will fix it and rename as ieee80211_txq_can_transmit().

Cool. If you send an updated patchset I can fold it into an updated
version of my RFC and send it as a proper patch once I've verified
everything works with ath9k :)

Thanks Toke for your feedback.

You're welcome! And thanks for working on this :)

-Toke