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Re: [tsvwg] [Ecn-sane] per-flow scheduling

Jonathan Morton <chromatix99@gmail.com> Thu, 18 July 2019 05:30 UTC

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From: Jonathan Morton <chromatix99@gmail.com>
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Date: Thu, 18 Jul 2019 08:30:28 +0300
Cc: "David P. Reed" <dpreed@deepplum.com>, Bob Briscoe <ietf@bobbriscoe.net>, "ecn-sane@lists.bufferbloat.net" <ecn-sane@lists.bufferbloat.net>, tsvwg IETF list <tsvwg@ietf.org>
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To: Dave Taht <dave.taht@gmail.com>
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Subject: Re: [tsvwg] [Ecn-sane] per-flow scheduling
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> On 18 Jul, 2019, at 3:20 am, Dave Taht <dave.taht@gmail.com> wrote:
> 
>> What it should do instead is peek the queue and drop until it hits a
>> markable packet, at the very least.
> 
> I didn't say this well. It should drop otherwise markable packets until it
> exits the loop, and then mark the one it delivers from that flow, if it delivers
> one from that flow. That gets rid of all the extra mass ecn creates...

You know, I think I finally understand what you're talking about here.  You want to treat cases where the marking rate exceeds the flow's packet delivery rate as an overload condition justifying a shift to packet drops.

This actually seems like a sane idea.  There is I think one caveat: selecting the Codel 'interval' parameter will now have an increased penalty for getting it wrong, especially on the too-small side.

 - Jonathan Morton

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