Re: [Make-wifi-fast] [RFC] ath10k: implement dql for htt tx

[Michal Kazior <michal.kazior@tieto.com>]

On 29 March 2016 at 17:54, Ben Greear <greearb@candelatech.com> wrote:
> On 03/29/2016 12:49 AM, Michal Kazior wrote:
>
>>> if you are getting a pure codel result of 160ms, that means the
>>> implementation is broken. But I think (after having read your
>>> description twice), the baseline result today of 160ms of queuing was
>>> with a fq_codel *qdisc* doing the work on top of huge buffers,
>>
>>
>> Yes. The 160ms is with fq_codel qdisc with ath10k doing DQL at 6mbps.
>> Without DQL ath10k would clog up all tx slots (1424 of them) with
>> frames. At 6mbps you typically want/need a handful (5-10) of frames to
>> be queued.
>
>
> Have you actually verified you can use all tx slots?

It works in most cases. I guess you're suspecting some of your
tx(flushing?) problems might be induced by overcommiting?

> The way the
> firmware uses it's tx buffers I think you may not be able to actually
> do that...and in practice, you will get a lot fewer usable tx-buffers
> than configured....

Could be, e.g. I'm aware management frames are kind of a special case
in recent firmware revisions.

What would/do you expect firmware would/will do when we overcommit?
The driver does advertise number of HTT tx slots so I would expect it
to work fine if it didn't crash during boot.


Michał