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 for ath10k@lists.infradead.org; Tue, 19 Apr 2016 15:35:43 +0000
From: "Valo, Kalle" <kvalo@qca.qualcomm.com>
Subject: Re: ath10k performance, master branch from 20160407
Date: Tue, 19 Apr 2016 15:35:16 +0000
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In-Reply-To: <CA+BoTQmn_hS1X1BjC7=wmevnAGiPx7iit0NMUxnmmqjFZ_RnVA@mail.gmail.com>	(Michal
 Kazior's message of "Tue, 19 Apr 2016 09:43:31 +0200")
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To: "michal.kazior@tieto.com" <michal.kazior@tieto.com>
Cc: Roman Yeryomin <leroi.lists@gmail.com>, "Manoharan,
 Rajkumar" <rmanohar@qti.qualcomm.com>, "ath10k@lists.infradead.org" <ath10k@lists.infradead.org>, Rajkumar Manoharan <rmanohar@codeaurora.org>

Michal Kazior <michal.kazior@tieto.com> writes:

> 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:
>>
>>> 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.

But we should never go backwards and TCP dropping from 750 Mbps to ~550
Mbps is a huge drop, so this is not ok. We have to do something to fix
this, be it reverting the wake_tx_queue support, somehow disabling it by
default or something.

-- 
Kalle Valo
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