Subject: Re: [PATCH 1/6] mt76: use mac80211 txq scheduling
To:     =?UTF-8?Q?Toke_H=c3=b8iland-J=c3=b8rgensen?= <toke@redhat.com>,
        linux-wireless@vger.kernel.org
References: <20190316204242.73560-1-nbd@nbd.name> <87muluv4hd.fsf@toke.dk>
From:   Felix Fietkau <nbd@nbd.name>
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Date:   Sun, 17 Mar 2019 11:44:32 +0100
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On 2019-03-16 23:28, Toke Høiland-Jørgensen wrote:
> Felix Fietkau <nbd@nbd.name> writes:
> 
>> Performance improvement and preparation for adding airtime fairness
>> support
> 
> Great to see this! Do you have a plan for the airtime fairness part?
> I.e., how to get the airtime information?
Not yet. Still need to investigate what kind of information the hardware
can provide. On a first glance it seems rather limited, so we may have
to approximate based on tx status rates/retry and average packet size.

> The call to ieee80211_return_txq() is really meant to be unconditional.
> The TXQ will only actually be scheduled if it still has packets queued.
> I know it's slightly more expensive to have the check in mac80211, but
> this is what makes it possible to change the implementation without
> touching the drivers (such as in the RFC patch I sent earlier that
> switches the scheduling algorithm)...
I think this API needs to be extended to allow the driver to specify
that it has buffered packets for a txq. Otherwise there's a small window
where the driver has packets for a txq but mac80211 doesn't, and
mac80211 won't schedule the queue in that case.
I'll send a patch for this soon.

- Felix