Re: [tcpm] I-D Action: draft-ietf-tcpm-hystartplusplus-12.txt

[Gorry Fairhurst <[e-mail]>]

On 12/01/2023 01:08, Neal Cardwell wrote:
> Your proposal to remove the description of the Linux TCP experience 
> from the "Deployments and Performance Evaluations" section sounds very 
> reasonable to me. I don't have any concerns with removing that 
> completely. I agree that it mostly just seems to cause confusion.
>
> thanks,
> neal
>
Thanks for explaining, I was one who had been confused and this 
explanation was appreciated. The proposed resolution would I agree avoid 
further confusion as people try to understand what was deployed.

Gorry

>
> On Wed, Jan 11, 2023 at 6:47 PM Praveen Balasubramanian 
> <[e-mail]> wrote:
>
>     I see, thanks Neal for the clarification. I then suggest that we
>     eliminate this deployment experience line completely because its
>     not with the proposed algorithm in this document and that it will
>     confuse new developers as to why the document suggests using
>     pacing with L=infinity when the default in Linux contradicts it.
>
>     Any concerns with just removing this line entirely?
>
>     On Wed, Jan 11, 2023 at 2:07 PM Neal Cardwell
>     <[e-mail]> wrote:
>
>         Martin pointed out out-of-band that my various attempts at
>         explaining this point have not been clear, so let me try to
>         express this a different way:
>
>         For about the last decade the Linux TCP default has been: [
>         CUBIC + Hystart + L=infinity + unpaced ]. This is because the
>         commonly deployed qdiscs for the major Linux distributions do
>         not implement pacing.
>
>         For 2013-2016 Google/YouTube Linux TCP ran with: [ CUBIC +
>         Hystart + L=infinity + paced ]. This was using the fq qdisc to
>         implement pacing.
>
>         best regards,
>         neal
>
>
>         On Tue, Jan 10, 2023 at 10:24 AM Neal Cardwell
>         <[e-mail]> wrote:
>
>             Looks like there is still one significant word in the
>             "Deployments and Performance Evaluations" section that
>             needs to be updated to be accurate.
>
>             Existing draft-ietf-tcpm-hystartplusplus-12 text:
>
>               There has been over a decade of experience using the
>               original Hystart algorithm for all TCP connections in the
>               Linux operating system with pacing *enabled* and an
>               actual L = infinity.
>
>             Suggested text:
>
>               There has been over a decade of experience using the
>               original Hystart algorithm for all TCP connections in the
>               Linux operating system with pacing *disabled* and an
>               actual L = infinity.
>
>             I mentioned the rationale in the "Re: [tcpm] Changes to
>             draft-ietf-tcpm-hystartplusplus after WGLC" thread on Nov 29:
>
>             https://mailarchive.ietf.org/arch/msg/tcpm/CSzCgxxSLrO9u63dymyyxqB6bD4/
>
>             cheers,
>             neal
>
>
>             On Mon, Jan 9, 2023 at 8:53 PM <[e-mail]>
>             wrote:
>
>
>                 A New Internet-Draft is available from the on-line
>                 Internet-Drafts directories.
>                 This draft is a work item of the TCP Maintenance and
>                 Minor Extensions WG of the IETF.
>
>                         Title           : HyStart++: Modified Slow
>                 Start for TCP
>                         Authors         : Praveen Balasubramanian
>                                           Yi Huang
>                                           Matt Olson
>                   Filename        : draft-ietf-tcpm-hystartplusplus-12.txt
>                   Pages           : 9
>                   Date            : 2023-01-09
>
>                 Abstract:
>                    This document describes HyStart++, a simple
>                 modification to the slow
>                    start phase of congestion control algorithms.
>                 Traditional slow start
>                    can overshoot the ideal send rate in many cases,
>                 causing high packet
>                    loss and poor performance.  HyStart++ uses a delay
>                 increase heuristic
>                    to find an exit point before possible overshoot. 
>                 It also adds a
>                    mitigation to prevent jitter from causing premature
>                 slow start exit.
>
>
>                 The IETF datatracker status page for this draft is:
>                 https://datatracker.ietf.org/doc/draft-ietf-tcpm-hystartplusplus/
>
>                 There is also an htmlized version available at:
>                 https://datatracker.ietf.org/doc/html/draft-ietf-tcpm-hystartplusplus-12
>
>                 A diff from the previous version is available at:
>                 https://author-tools.ietf.org/iddiff?url2=draft-ietf-tcpm-hystartplusplus-12
>
>
>                 Internet-Drafts are also available by rsync at
>                 rsync.ietf.org::internet-drafts
>
>
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