DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 702322086A
Subject: Re: [Make-wifi-fast] [PATCH v3 3/6] mac80211: Add airtime accounting
 and scheduling to TXQs
To:     Dave Taht <dave.taht@gmail.com>,
        Simon Barber <simon@superduper.net>
References: <1542063113-22438-1-git-send-email-rmanohar@codeaurora.org>
 <1542063113-22438-4-git-send-email-rmanohar@codeaurora.org>
 <e5344cad-2a18-a938-f2ed-43870027251c@nbd.name> <871s7nv9pl.fsf@toke.dk>
 <8e7847ff-4c88-10ae-2223-2fc7321641d9@nbd.name> <87sh02tfsp.fsf@toke.dk>
 <878t1p2bqz.fsf@taht.net> <87muq4sn50.fsf@toke.dk>
 <4DD985B6-7DBE-42F8-AC87-D6B40CEAE553@superduper.net>
 <CAA93jw4Cih5HkHYUOy7Vr5G7zi0KkKmNnNohDAVaj65goWOh+A@mail.gmail.com>
Cc:     =?UTF-8?Q?Toke_H=c3=b8iland-J=c3=b8rgensen?= <toke@toke.dk>,
        Rajkumar Manoharan <rmanohar@codeaurora.org>,
        Make-Wifi-fast <make-wifi-fast@lists.bufferbloat.net>,
        linux-wireless <linux-wireless@vger.kernel.org>,
        ath10k <ath10k@lists.infradead.org>, Felix Fietkau <nbd@nbd.name>
From:   Ben Greear <greearb@candelatech.com>
Organization: Candela Technologies
Message-ID: <b0662c97-fb17-3f9d-693e-2fec92535076@candelatech.com>
Date:   Mon, 19 Nov 2018 15:56:09 -0800
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101
 Thunderbird/45.0
MIME-Version: 1.0
In-Reply-To: <CAA93jw4Cih5HkHYUOy7Vr5G7zi0KkKmNnNohDAVaj65goWOh+A@mail.gmail.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 8bit
Sender: linux-wireless-owner@vger.kernel.org
Precedence: bulk

On 11/19/2018 03:47 PM, Dave Taht wrote:
> On Mon, Nov 19, 2018 at 3:30 PM Simon Barber <simon@superduper.net> wrote:
>>
>>
>>
>> On Nov 19, 2018, at 2:44 PM, Toke Høiland-Jørgensen <toke@toke.dk> wrote:
>>
>> Dave Taht <dave@taht.net> writes:
>>
>> Toke Høiland-Jørgensen <toke@toke.dk> writes:
>>
>> Felix Fietkau <nbd@nbd.name> writes:
>>
>> On 2018-11-14 18:40, Toke Høiland-Jørgensen wrote:
>>
>> This part doesn't really make much sense to me, but maybe I'm
>> misunderstanding how the code works.
>> Let's assume we have a driver like ath9k or mt76, which tries to keep a
>>
>> ….
>>
>>
>> Well, there's going to be a BQL-like queue limit (but for airtime) on
>> top, which drivers can opt-in to if the hardware has too much queueing.
>>
>>
>> Very happy to read this - I first talked to Dave Taht about the need for Time Queue Limits more than 5 years ago!
>
> Michal faked up a dql estimator 3 (?) years ago. it worked.
>
> http://blog.cerowrt.org/post/dql_on_wifi_2/
>
> As a side note, in *any* real world working mu-mimo situation at any
> scale, on any equipment, does anyone have any stats on how often the
> feature is actually used and useful?
>
> My personal guess, from looking at the standard, was in home
> scenarios, usage would be about... 0, and in a controlled environment
> in a football stadium, quite a lot.
>
> In a office or apartment complex, I figured interference and so forth
> would make it a negative benefit due to retransmits.
>
> I felt when that part of the standard rolled around... that mu-mimo
> was an idea that should never have escaped the lab. I can be convinced
> by data, that we can aim for a higher goal here. But it would be
> comforting to have a measured non-lab, real-world, at real world
> rates, result for it, on some platform, of it actually being useful.

We're working on building a lab with 20 or 30 mixed 'real' devices
using various different /AC NICs (QCA wave2 on OpenWRT, Fedora, realtek USB 8812au on OpenWRT, Fedora,
and some Intel NICs in NUCs on Windows, and maybe more).  I'm not actually sure if that realtek
  or the NUCs can do MU-MIMO or not, but the QCA NICs will be able to.  It should be at least somewhat similar
to a classroom environment or coffee shop.  I'll let you know what we find
as far as how well MU-MIMO improves things or not.

At least in simple test cases (one 1x1 stations, one 2x2 station, with 4x4 MU-MIMO AP),
it works very well for increased download throughput.

In home setups, I'd guess that the DSL or Cable Modem or other uplink is the bottleneck
way more often than the wifi is, even if your are just running /n.  But, maybe that is just
my experience living out at the end of a long skinny phone line all these years.

Thanks,
Ben


-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com