[Make-wifi-fast] How to figure out Linux wifi queue and ath10k queue scheduling?

Louie Lu nctu at louie.lu
Wed Nov 22 10:35:21 EST 2017

2017-11-22 22:25 GMT+08:00 Toke Høiland-Jørgensen <toke at toke.dk>:
> Hi Louie
>> I'm working on making VoWIFI performance more better on ath10k driver,
>> my first thought is that I can modify queue scheduling algorithm
>> inside ath10k.
> Sounds awesome! What kind of VoIP traffic are you working with, and what
> aspect of performance are you looking to improve? :)

We are working on 802.11ac with telecom operator's VoWIFI (through ePDG),
but much more focus on the phone to AP jitter, latency and TXOP when
AP has multiple stations (10+) traffic.

>> After tracking the commit log, it seems currently ath10k is using
>> mac80211 as an intermidieate queue[1][2], and as [2] indicate, ath10k
>> is not able to do airtime fairness now.
> Yup, that's about right. We're working on the airtime fairness part,
> though; see my recent presentation at Netdev a few weeks ago for an
> updated status on previous and ongoing work [1].

Thanks for the update, I'll take a look at this. Also, is "airetime
fairness" a concept as fair TXOP
to each station? I'm not sure if I get this right.

>> After reading the source code and [2], what I think about the queue in
>> Linux to ath10k is:
>> 1. Mac layer queue (mac80211)
>> 2. ath10k 802.11e priority queues (4 queues, with different 802.11e ToS level)
>> 3. ath10k firmware (HW) queue
>> Am I right on this?
> More or less (I don't know enough about how ath10k works internally to
> tell you exactly how the internal queueing in the driver works).
> Ideally, the lower-level queues (2 and 3) should be as empty as
> possible, but no one ever got around to working on improving that. There
> was an aborted attempt to apply the dynamic queue limit code[2] to
> ath10k a while ago, but it was never completed. The WiP commit is here:
> [3].

Thanks for the information, I'll take a look at it.

>> Also, I saw the make-wifi-fast google docs[3], it has a plan for
>> obsolete VO queue, is that still in the roadmap, or it is implemented,
>> if not, where can I help for it?
> The work on the different QoS levels has mostly been on the idea stage
> so far. My presentation[1] has some ideas related to this as well, but
> nothing has been implemented thus far. What's on the roadmap depends
> mostly on what people go ahead and implement ;)

Got it, but are there any udpate about the make-wifi-fast google docs?
Or this is
the latest version of it. Beside patchwork, is there an issue tracker
or just mailing list
to get the latest information?


> -Toke
> [1] https://www.netdevconf.org/2.2/session.html?jorgensen-wifistack-talk
> [2] https://lwn.net/Articles/454390/
> [3] https://github.com/kazikcz/linux/commit/1486ffbafdb4dd433203c35c694b7443fa769210

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