From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-x243.google.com (mail-lf0-x243.google.com [IPv6:2a00:1450:4010:c07::243]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id A38313B2A4; Thu, 21 Jun 2018 11:31:31 -0400 (EDT) Received: by mail-lf0-x243.google.com with SMTP id g21-v6so4942325lfb.4; Thu, 21 Jun 2018 08:31:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=XlQgvUrt+IWDxfDk0DksnR6elWkGST2kP+hsZ+Dl1m4=; b=t+3ytnsLM7DGiHqJZP+e0aFuhETHoPzt5bs/ykAqbw1PTA0sFq0zjxRStiGCsziXv7 wJ8aCfUqAsozr0Jt7ic3h/rlt3MJwzQU70GIOGMXxGAO4uMDmZlhzKKeclwV8RfmSSbk mgd00fIBNv/SCNXXikAljz++iCYxMuXX5QCiZafomV3wi/29bYfJh0ciwpTBY5H2ikhr KKyKRpzKU5Gc+ouRaTh4JIFbogVFsRWfBf0Abkkt3xAVjzAWYnYPqAHCe6qO6L9f9wv7 dybq+0ERILGdbR3+zMDnFG9NenGZHDO3HqI3UnvrznIDAEarZvKWDpIJ+lbOovMMdhiM MaQQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=XlQgvUrt+IWDxfDk0DksnR6elWkGST2kP+hsZ+Dl1m4=; b=uOrHFwl1AmQsbEzACJ7ZArJvMXIXpnI0FLiMi81xbmranFErld3HMBVZJ4wGRPIDQm xJtdm5J2zU25qB4AYRBhuLIWBZYMfOyCzTEDJH4SjDwisrDCPDY7SajMw70NITzmCxqt geIMhO9XQn/qcaig0fr9Wgq7lEvj+spIim4BrJcdxPm/iKzEHTPwqKEQTtLp9P9tqU4z taemww4OmcHDgMG6tW50ziT0eGly77whoqxPiQVv3SxdNfTvO5GEmAqGzJC3032fHx2W XNqI9cXu0zlkhHoRVj4dJqUhiZdE/oRS1SP3UcxklYCprl062n4nLeT9pkaNt9LjM6Y3 McwQ== X-Gm-Message-State: APt69E0/xyp8br3QW679MqYOE9ZBqZQtDW+EPRK0NrH9JRJl6p//UXfB n1d4aQ5nyTA9KKfbUTGmKx1sjexTVyvngbR2hZM= X-Google-Smtp-Source: ADUXVKKqT4YKq4NFIMBNX/dkNVlIz8OcD1Ro8v61+5C8EgbGfJAD5G7nQ+G4pjgEIMLB0HtZUZ44JPn7Vi4cFeWoLjI= X-Received: by 2002:a19:c203:: with SMTP id l3-v6mr8661592lfc.55.1529595090499; Thu, 21 Jun 2018 08:31:30 -0700 (PDT) MIME-Version: 1.0 References: <8736xgsdcp.fsf@toke.dk> <838b212e-7a8c-6139-1306-9e60bfda926b@gmail.com> In-Reply-To: From: Caleb Cushing Date: Thu, 21 Jun 2018 10:31:18 -0500 Message-ID: To: Dave Taht Cc: Eric Dumazet , Make-Wifi-fast , bloat Content-Type: multipart/alternative; boundary="00000000000004fdfe056f289c1d" X-Mailman-Approved-At: Thu, 21 Jun 2018 11:42:54 -0400 Subject: Re: [Make-wifi-fast] [Bloat] lwn.net's tcp small queues vs wifi aggregation solved X-BeenThere: make-wifi-fast@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 21 Jun 2018 15:31:32 -0000 --00000000000004fdfe056f289c1d Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable actually... all of my devices, including my desktop connect through wifi these days... and only one of them isn't running some variant of linux. On Thu, Jun 21, 2018 at 10:18 AM Dave Taht wrote: > On Thu, Jun 21, 2018 at 5:55 AM, Eric Dumazet > wrote: > > > > > > On 06/21/2018 02:22 AM, Toke H=C3=B8iland-J=C3=B8rgensen wrote: > >> Dave Taht writes: > >> > >>> Nice war story. I'm glad this last problem with the fq_codel wifi cod= e > >>> is solved > >> > >> This wasn't specific to the fq_codel wifi code, but hit all WiFi devic= es > >> that were running TCP on the local stack. Which would be mostly laptop= s, > >> I guess... > > > > Yes. > > > > Also switching TCP stack to always GSO has been a major gain for wifi i= n > my tests. > > > > (TSQ budget is based on sk_wmem_alloc, tracking truesize of skbs, and > not having > > GSO is considerably inflating the truesize/payload ratio) > > > > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit= /?id=3D0a6b2a1dc2a2105f178255fe495eb914b09cb37a > > tcp: switch to GSO being always on > > > > I expect SACK compression to also give a nice boost to wifi. > > > > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit= /?id=3D5d9f4262b7ea41ca9981cc790e37cca6e37c789e > > tcp: add SACK compression > > > > Lastly I am working on adding ACK compression in TCP stack itself. > > One thing I've seen repeatedly on mac80211 aircaps is a tendency for > clients to use up two TXOPs rather than one. > > scenario: > > 1) A tcp burst arrives at the client > 2) A single ack migrates down the client stack into the driver, into > the device, which then attempts to compete for airtime on that TXOP > for that single ack, sometimes waiting 10s of msec to get that op > 3) a bunch more acks arrive "slightly late"[1], and then get queued > for the next TXOP, waiting, again sometimes 10s of msec > > (similar scenario in a client making a quick string of web related > requests) > > This is a case where inserting a teeny bit more latency to fill up the > queue (ugh!), or a driver having some way to ask the probability of > seeing more data in the > next 10us, or... something like that, could help. > > ... > > [1] if you need coffee through your nose this morning, regarding usage > of the phrase "slightly late", read > http://www.rawbw.com/~svw/superman.html > > -- > > Dave T=C3=A4ht > CEO, TekLibre, LLC > http://www.teklibre.com > Tel: 1-669-226-2619 <(669)%20226-2619> > _______________________________________________ > Bloat mailing list > Bloat@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/bloat > --=20 Caleb Cushing http://xenoterracide.com --00000000000004fdfe056f289c1d Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
actually... all of my devices, including my desktop connec= t through wifi these days... and only one of them isn't running some va= riant of linux.

On Thu= , Jun 21, 2018 at 10:18 AM Dave Taht <dave.taht@gmail.com> wrote:
On Thu, Jun 21, 2018 at 5:55 AM, Eric Dumazet <eric.dumazet@gmail.com> wrot= e:
>
>
> On 06/21/2018 02:22 AM, Toke H=C3=B8iland-J=C3=B8rgensen wrote:
>> Dave Taht <dave.taht@gmail.com> writes:
>>
>>> Nice war story. I'm glad this last problem with the fq_cod= el wifi code
>>> is solved
>>
>> This wasn't specific to the fq_codel wifi code, but hit all Wi= Fi devices
>> that were running TCP on the local stack. Which would be mostly la= ptops,
>> I guess...
>
> Yes.
>
> Also switching TCP stack to always GSO has been a major gain for wifi = in my tests.
>
> (TSQ budget is based on sk_wmem_alloc, tracking truesize of skbs, and = not having
> GSO is considerably inflating the truesize/payload ratio)
>
> https://git.kernel.org/pub/scm/linux/kernel/git/to= rvalds/linux.git/commit/?id=3D0a6b2a1dc2a2105f178255fe495eb914b09cb37a<= br> > tcp: switch to GSO being always on
>
> I expect SACK compression to also give a nice boost to wifi.
>
> https://git.kernel.org/pub/scm/linux/kernel/git/to= rvalds/linux.git/commit/?id=3D5d9f4262b7ea41ca9981cc790e37cca6e37c789e<= br> > tcp: add SACK compression
>
> Lastly I am working on adding ACK compression in TCP stack itself.

One thing I've seen repeatedly on mac80211 aircaps is a tendency for clients to use up two TXOPs rather than one.

scenario:

1) A tcp burst arrives at the client
2) A single ack migrates down the client stack into the driver, into
the device, which then attempts to compete for airtime on that TXOP
for that single ack, sometimes waiting 10s of msec to get that op
3) a bunch more acks arrive "slightly late"[1], and then get queu= ed
for the next TXOP, waiting, again sometimes 10s of msec

(similar scenario in a client making a quick string of web related requests= )

This is a case where inserting a teeny bit more latency to fill up the
queue (ugh!), or a driver having some way to ask the probability of
seeing more data in the
next 10us, or... something like that, could help.

...

[1] if you need coffee through your nose this morning, regarding usage
of the phrase "slightly late", read
http://www.rawbw.com/~svw/superman.html

--

Dave T=C3=A4ht
CEO, TekLibre, LLC
ht= tp://www.teklibre.com
Tel: 1-669-226-2619
_______________________________________________
Bloat mailing list
Bloat@list= s.bufferbloat.net
https://lists.bufferbloat.net/listinfo/bloat
--
Caleb Cushing

<= div>http://xenoterracide.com
=
--00000000000004fdfe056f289c1d--