Re: [quicwg/base-drafts] HTTP/3 with strict priorities (#2700)

Igor Lubashev <> Mon, 20 May 2019 16:52 UTC

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From: Igor Lubashev <>
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Subject: Re: [quicwg/base-drafts] HTTP/3 with strict priorities (#2700)
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@rmarx, I would not say that odd priority values _represent_ odd concurrency level 3.  You could implement @pmeenan's "concurrency level 3" that way.  But the idea is that you do not need "concurrency level 3" as a special case to think about.

There are just two criteria:

1. Priorities:  Elements of the higher priority 100% preempt elements of the lower priority.

2. Concurrency: Elements of the same priority share bandwidth.  Serial elements need to be downloaded to completion one at a time, while concurrent elements need to be downloaded concurrently.  There is still a question of how serial and concurrent elements share bandwidth.  There is a proposal that concurrent elements get 50% of the bandwidth as a group.  The alternative is that concurrent elements group gets a percentage proportional to the number of concurrent elements in at that priority level. Both of these alternatives seem "hacky" as they possible do not give the client sufficient control for bandwidth sharing.  I have some proposal and will share it on the list (the PR comment does not seem like the right place for it).

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