Re: ath10k performance, master branch from 20160407

[Roman Yeryomin <leroi.lists@gmail.com>]

On 19 April 2016 at 10:43, Michal Kazior <michal.kazior@tieto.com> wrote:
> On 19 April 2016 at 09:31, Roman Yeryomin <leroi.lists@gmail.com> wrote:
>> On 19 April 2016 at 08:28, Michal Kazior <michal.kazior@tieto.com> wrote:
>>> On 18 April 2016 at 15:00, Roman Yeryomin <leroi.lists@gmail.com> wrote:
>>>> So it looks like Michal's patch set "ath10k: implement push-pull tx
>>>> model" introduced this regression - after restoring it from reverts
>>>> fq_codel_drop is hungry again.
>>>> Any ideas how to fix?
>>>
>>> If my hunch is right there's no easy (and proper) fix for that now.
>>>
>>> One of the patchset patches (ath10k: implement wake_tx_queue) starts
>>> to use mac80211 software queuing. This introduces extra induced
>>> latency and I'm guessing it results in fill-in-then-drain sequences in
>>> some cases which end up being long enough to make fq_codel_drop more
>>> work than normal.
>>>
>>> This is required for other changes and MU-MIMO performance
>>> improvements so this patch can't be removed.
>>
>> But qca988x doesn't support MU-MIMO, AFAIK.
>
> Correct.
>
>
>> Can this be made chip dependent?
>
> I guess it could but it'd arguably make the driver more complex and
> harder to maintain. What we want is a long-term fix, not a short-term
> one.
>
> The long-term fix is a work-in-progress which aims at killing
> bufferbloat in general [1][2]. This should, by proxy, improve
> everything.
>
> [1]: https://www.spinics.net/lists/linux-wireless/msg149776.html
> [2]: https://www.spinics.net/lists/linux-wireless/msg148714.html
> [3]: https://www.spinics.net/lists/linux-wireless/msg149039.html
>
> You can try out patchset from [1] (and maybe [3] as well) to see if it
> helps you (assuming you have spare time to play around).

Will try.

Regards,
Roman

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