ath10k performance, master branch from 20160407

Roman Yeryomin leroi.lists at
Sun May 15 15:59:40 PDT 2016

On 9 May 2016 at 15:26, Michal Kazior <michal.kazior at> wrote:
> Hi Roman,
> On 22 April 2016 at 19:05, Roman Yeryomin <leroi.lists at> wrote:
>> On 19 April 2016 at 18:35, Valo, Kalle <kvalo at> wrote:
>>> Michal Kazior <michal.kazior at> writes:
>>>> On 19 April 2016 at 09:31, Roman Yeryomin <leroi.lists at> wrote:
>>>>> On 19 April 2016 at 08:28, Michal Kazior <michal.kazior at> 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.
>> I would agree with Kalle here. This looks like very serious regression.
>> But I'm afraid I can only help with testing here.
> Can you give the following patch a try, please? I didn't get to
> reproduce your problem on a real AP135/AP152 board and instead tried
> to simulate a slow uni-proc system via KVM and cooling_device in
> sysfs. The patch does improve things in this synthetic setup for me.

Unfortunately doesn't seem to make any difference at all (really, if
there is, it's less than 10Mbps).
Please see this thread also:
That is with your and Eric's patch applied.


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