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From: Dave Taht <dave@taht.net>
To: Luca Muscariello <luca.muscariello@gmail.com>
Cc: Sebastian Moeller <moeller0@gmx.de>,
	 bloat <bloat@lists.bufferbloat.net>
Subject: Re: [Bloat] benefits of ack filtering
Date: Fri, 01 Dec 2017 10:43:22 -0800	[thread overview]
Message-ID: <874lpagugl.fsf@nemesis.taht.net> (raw)
In-Reply-To: <CAHx=1M5GG7BErHvG3ntvyUKv02CMMj8M=XftqzGM_+7JDxHPqQ@mail.gmail.com> (Luca Muscariello's message of "Fri, 1 Dec 2017 11:45:19 +0100")

Luca Muscariello <luca.muscariello@gmail.com> writes:

> For highly asymmetric links, but also shared media like wifi, QUIC might be a
> better playground for optimisations.
> Not pervasive as TCP though and maybe off topic in this thread.

I happen to really like QUIC, but a netperf-style tool did not exist for
it when I last looked, last year.

Also getting to emulating DASH traffic is on my list.

>
> If the downlink is what one want to optimise, using FEC in the downstream, in
> conjunction with flow control could be very effective.
> No need to send ACK frequently and having something like FQ_codel in the
> downstream would avoid fairness problems that might
> happen though. I don't know if FEC is still in QUIC and used.
>
> BTW, for wifi, the ACK stream can be compressed in aggregate of frames and sent
> in bursts. This is similar to DOCSIS upstream.
> I wonder if this is a phenomenon that is visible in recent WiFi or just
> negligible.

My guess is meraki deployed something and I think they are in in the top
5 in the enterprise market.

I see ubnt added airtime fairness (of some sort), recently.

>
> On Fri, Dec 1, 2017 at 9:45 AM, Sebastian Moeller <moeller0@gmx.de> wrote:
>
>     Hi All,
>     
>     you do realize that the worst case is going to stay at 35KPPS? If we assume
>     simply that the 100Mbps download rate is not created by a single flow but by
>     many flows (say 70K flows) the discussed ACK frequency reduction schemes
>     will not work that well. So ACK thinning is a nice optimization, but will
>     not help the fact that some ISPs/link technologies simply are asymmetric and
>     the user will suffer under some traffic conditions. Now the 70K flow example
>     is too extreme, but the fact is at hight flow number with sparse flows (so
>     fewer ACKs per flow in the queue and fewer ACKs per flow reaching the end
>     NIC in a GRO-collection interval (I naively assume there is a somewhat fixed
>     but small interval in which packets of the same flow are collected for GRO))
>     there will be problems. (Again, I am all for allowing the end user to
>     configure ACK filtering thinning, but I would rather see ISPs sell less
>     imbalanced links ;) )
>     
>     Best Regards
>     Sebastian
>     
>     
>     
>     > On Dec 1, 2017, at 01:28, David Lang <david@lang.hm> wrote:
>     >
>     > 35K PPS of acks is insane, one ack every ms is FAR more than enough to do
>     'fast recovery', and outside the datacenter, one ack per 10ms is probably
>     more than enough.
>     >
>     > Assuming something that's not too assymetric, thinning out the acks may
>     not make any difference in the transfer rate of a single data flow in one
>     direction, but if you step back and realize that there may be a need to
>     transfer data in the other direction, things change here.
>     >
>     > If you have a fully symmetrical link, and are maxing it out in both
>     direction, going from 35K PPs of aks competing with data packets and gonig
>     down to 1k PPS or 100 PPS (or 10 PPS) would result in a noticable
>     improvement in the flow that the acks are competing against.
>     >
>     > Stop thinking in terms of single-flow benchmarks and near idle 'upstream'
>     paths.
>     >
>     > David Lang
>     > _______________________________________________
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>     > Bloat@lists.bufferbloat.net
>     > https://lists.bufferbloat.net/listinfo/bloat
>     
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  reply	other threads:[~2017-12-01 18:43 UTC|newest]

Thread overview: 76+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-28 21:48 Dave Taht
2017-11-29  6:09 ` Mikael Abrahamsson
2017-11-29  9:34   ` Sebastian Moeller
2017-11-29 12:49     ` Mikael Abrahamsson
2017-11-29 13:13       ` Luca Muscariello
2017-11-29 14:31         ` Mikael Abrahamsson
2017-11-29 14:36           ` Jonathan Morton
2017-11-29 15:24             ` Andrés Arcia-Moret
2017-11-29 15:53           ` Luca Muscariello
     [not found]             ` <CAJq5cE3qsmy8EFYZmQsLL_frm8Tty9Gkm92MQPZ649+kpM1oMw@mail.gmail.com>
2017-11-29 16:13               ` Jonathan Morton
2017-11-30  7:03             ` Michael Welzl
2017-11-30  7:24               ` Dave Taht
2017-11-30  7:45               ` Dave Taht
2017-11-30  7:48               ` Jonathan Morton
2017-11-30  8:00                 ` Luca Muscariello
2017-11-30 10:24                 ` Eric Dumazet
2017-11-30 13:04                   ` Mikael Abrahamsson
2017-11-30 15:51                     ` Eric Dumazet
2017-12-01  0:28                     ` David Lang
2017-12-01  7:09                       ` Jan Ceuleers
2017-12-01 12:53                         ` Toke Høiland-Jørgensen
2017-12-01 13:13                           ` [Bloat] [Make-wifi-fast] " Кирилл Луконин
2017-12-01 13:22                             ` Luca Muscariello
2017-12-11 17:42                             ` Simon Barber
2017-12-01 13:17                           ` [Bloat] " Luca Muscariello
2017-12-01 13:40                             ` Toke Høiland-Jørgensen
2017-12-01 17:42                               ` Dave Taht
2017-12-01 20:39                                 ` Juliusz Chroboczek
2017-12-03  5:20                                   ` [Bloat] [Make-wifi-fast] " Bob McMahon
2017-12-03 10:35                                     ` Juliusz Chroboczek
2017-12-03 11:40                                       ` Jan Ceuleers
2017-12-03 13:57                                         ` Juliusz Chroboczek
2017-12-03 14:07                                           ` Mikael Abrahamsson
2017-12-03 19:53                                             ` Juliusz Chroboczek
2017-12-03 14:09                                           ` Ryan Mounce
2017-12-03 19:54                                             ` Juliusz Chroboczek
2017-12-03 20:14                                               ` Sebastian Moeller
2017-12-03 22:27                                                 ` Dave Taht
2017-12-03 15:25                                           ` Robert Bradley
2017-12-04  3:44                                         ` Dave Taht
2017-12-04 14:38                                           ` David Collier-Brown
2017-12-04 15:44                                             ` Juliusz Chroboczek
2017-12-04 17:17                                               ` David Collier-Brown
2017-12-03 19:04                                       ` Bob McMahon
2017-12-01 21:17                                 ` Bob McMahon
2017-12-01  8:45                       ` [Bloat] " Sebastian Moeller
2017-12-01 10:45                         ` Luca Muscariello
2017-12-01 18:43                           ` Dave Taht [this message]
2017-12-01 18:57                             ` Luca Muscariello
2017-12-01 19:36                               ` Dave Taht
2017-11-30 14:51                   ` Neal Cardwell
2017-11-30 15:55                     ` Eric Dumazet
2017-11-30 15:57                       ` Neal Cardwell
2017-11-29 16:50       ` Sebastian Moeller
2017-12-12 19:27         ` Benjamin Cronce
2017-12-12 20:04           ` Dave Taht
2017-12-12 21:03           ` David Lang
2017-12-12 21:29             ` Jonathan Morton
2017-12-12 22:03           ` Jonathan Morton
2017-12-12 22:21             ` David Lang
     [not found]               ` <CAJq5cE3nfSQP0GCLjp=X0T-iHHgAs=YUCcr34e3ARgkrGZe-wg@mail.gmail.com>
2017-12-12 22:41                 ` Jonathan Morton
2017-12-13  9:46                   ` Mikael Abrahamsson
2017-12-13 10:03                     ` Jonathan Morton
2017-12-13 12:11                       ` Sebastian Moeller
2017-12-13 12:18                         ` Jonathan Morton
2017-12-13 12:36                     ` Sebastian Moeller
2017-12-13 12:39             ` Luca Muscariello
2017-11-29 18:21   ` Juliusz Chroboczek
2017-11-29 18:41     ` Dave Taht
2017-11-29 23:29       ` Steinar H. Gunderson
2017-11-29 23:59       ` Stephen Hemminger
2017-11-30  0:21         ` Eric Dumazet
2017-12-11 20:15   ` Benjamin Cronce
2017-11-29 18:28 ` Juliusz Chroboczek
2017-11-29 18:48   ` Dave Taht
2017-12-11 18:30   ` Jonathan Morton

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