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From: Dave Taht <dave.taht@gmail.com>
To: Juliusz Chroboczek <jch@irif.fr>
Cc: bloat <bloat@lists.bufferbloat.net>,
	Cake List <cake@lists.bufferbloat.net>
Subject: Re: [Cake] [Bloat] benefits of ack filtering
Date: Wed, 29 Nov 2017 10:48:48 -0800	[thread overview]
Message-ID: <CAA93jw7tX_xg4+11Ja8mwZWZGGfMa1eyqx75Yfnn6GihdkjfLQ@mail.gmail.com> (raw)
In-Reply-To: <7izi75q6rj.wl-jch@irif.fr>

On Wed, Nov 29, 2017 at 10:28 AM, Juliusz Chroboczek <jch@irif.fr> wrote:
>> Recently Ryan Mounce added ack filtering cabilities to the cake qdisc.
>> The benefits were pretty impressive at a 50x1 Down/Up ratio:
>
> If I read this posting right, you're only measuring bulk performance.
> What about interactive traffic, when there's only one or two data segments in
> flight at a given time

In this design, you can only filter out an ack when you have a queue of them.

I am thinking saying "filter" has been misleading. Tho plenty
stateless ack filters exist.

ack-queue-compression?

>> I'd rather like to have a compelling list of reasons why not to do
>> this!
>
> I haven't looked at Cake in detail, and I haven't put much thought into
> ACK filtering, but off the top of my head:
>
>   - not risking breaking any of the TCP-related algorithms that depend on
>     ACKs arriving in a timely manner (AIMD, Nagle, Eifel, etc.),
>     especially in the case of just one segment in flight;
>   - not contributing to the ossification of the Internet by giving an
>     unfair advantage to TCP over other protocols;
>   - limiting the amount of knowledge that middleboxes have of the
>     transport-layer protocols, which leads to further ossification;
>   - avoiding complexity in middleboxes, which leads to a more brittle
>     Internet;
>   - not encouraging ISPs to deploy highly asymmetric links.

I'll add these to my list!

>
> This is not my area of expertise, and therefore I don't feel competent to
> have an opinion, but I think that before you deploy ACK filtering, you
> really should consider the worries expressed above and whatever other
> worries more competent people might have.

been worrying ever since I touched the wet paint!

> -- Juliusz



-- 

Dave Täht
CEO, TekLibre, LLC
http://www.teklibre.com
Tel: 1-669-226-2619

      parent reply	other threads:[~2017-11-29 18:48 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CAA93jw47ZAXAJmiOVCb2NR3JRcCfmX0TLr+55O0G+J6HCW5bVQ@mail.gmail.com>
     [not found] ` <alpine.DEB.2.20.1711290655590.32099@uplift.swm.pp.se>
     [not found]   ` <7i1skhrln1.wl-jch@irif.fr>
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
     [not found] ` <7izi75q6rj.wl-jch@irif.fr>
2017-11-29 18:48   ` Dave Taht [this message]

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