Re: [tcpm] Hystart survey of large server operators

Yuchung Cheng <ycheng@google.com> Tue, 27 July 2021 23:47 UTC

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In-Reply-To: <84ac0f00-b828-2503-fd7c-0ef7c6465768@bobbriscoe.net>
From: Yuchung Cheng <ycheng@google.com>
Date: Tue, 27 Jul 2021 16:46:21 -0700
Message-ID: <CAK6E8=f7qKDs-MFr4G6bpz82Swn3iCJEkWLL5yr+vV8z9zMb=Q@mail.gmail.com>
To: Bob Briscoe <ietf@bobbriscoe.net>
Cc: Praveen Balasubramanian <pravb@microsoft.com>, "tcpm@ietf.org" <tcpm@ietf.org>, "draft-ietf-tcpm-hystartplusplus@ietf.org" <draft-ietf-tcpm-hystartplusplus@ietf.org>, Neal Cardwell <ncardwell@google.com>
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Subject: Re: [tcpm] Hystart survey of large server operators
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Wait -- how is hystart "invariably disabled" in Linux (cubic)!?

What data indicates that

On Tue, Jul 27, 2021 at 4:37 PM Bob Briscoe <ietf@bobbriscoe.net> wrote:

> Any large server operator out there who are using Cubic,
> If you're willing to state whether or not your operations disable Hystart,
> pls do so in reply.
> Then Praveen can cite this mailing list thread in the Hystart++ draft, as
> requested below.
>
> If you are willing to reply privately, I would be willing to keep your
> confidences, and provide an anonymized result to the list.
>
> Cheers
>
>
>
> Bob
>
> On 27/07/2021 01:50, Praveen Balasubramanian wrote:
>
> Although Hystart is default enabled in Linux, it is invariably disabled. So, it's misleading to just say Hystart is default enabled, which implies it's widely used, when people clearly find it has problems (which motivates Hystart++). I found this out through an informal survey I did at the Mar'18 IETF in London by asking round the implementers of the most prevalent stacks (I would name names if I could find the note I later sent to someone or to some list, but I can't find it - sry).
>
> I'd like some citations on this versus anecdata if possible before I add that caveat to the text. Do large deployments disable this? I haven't come across this suggestion in any Linux tuning guides to date.
>
>
> --
> ________________________________________________________________
> Bob Briscoe                               http://bobbriscoe.net/
>
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