#1013: Paint/presentation timestamps in performance APIs

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Opened Nov 12, 2024

こんにちは TAG-さん!

I'm requesting an early TAG design review of Paint/presentation timestamps in performance APIs.

Aligning different paint-related timestamps in all the relevant performance APIs, by having one "interoperable" timestamp and one coarsened platform-specific "VSync" (or "pixels on screen") timestamp.

Further details:

  • I have reviewed the TAG's Web Platform Design Principles
  • The group where the incubation/design work on this is being done (or is intended to be done in the future):
  • The group where standardization of this work is intended to be done ("unknown" if not known):
  • Existing major pieces of multi-implementer review or discussion of this design:
  • Major unresolved issues with or opposition to this design:
  • This work is being funded by:

You should also know that...

This has been discussed in the WebPerfWG in detail over the last 2 years.

Discussions

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Discussed Jan 1, 2025 (See Github)

Amy: Both of these aren't very user needs forward. Talks about use cases but not end user experience. Probably implicit because it's performance, but it's useful to have them state that explicitly so we can weigh up tradeoffs

Matthew: second one missing "alternatives considered"

Matthew left a comment

Discussed Jan 1, 2025 (See Github)

Matthew: both of these (1012 and 1013) we asked for specific bits to be put in the explainer but no reply or updates on either...

Comment by @matatk Jan 15, 2025 (See Github)

Hi @noamr, thanks for this review request also. We have been discussing paint/presentation timestamps today too, and have a couple of question about the explainer. We would really like to see the (end-)user needs made explicit. We'd also like to know about the alternatives that were considered, and why they found to be unsuitable, again this helps us weigh up the trade-offs. Thank you in advance for any further info you can provide.

Just in case it eases future reference: we put some background info on explainers in the other thread

Discussed Feb 1, 2025 (See Github)

(still waiting on feedback after we commented, as below)

Discussed Mar 1, 2025 (See Github)

Matthew: Don't enough. It is interesting, and agree it should be more interoperable. Firefox is doing it. Not sure about WebKit. Signs are good. Curiousity is interoperable and implementation-metric. They give an explanation on why interoperable-metric is one or two things. Not sure how interoperable it is. Perhaps @xiaochengh could look into it.

Jeffrey: We should post something about direction looks good. Agree re having xiaochengh a look.

Jeffrey: Hope to post something in plenary.