Presentation extension RFCv2, feedback implemented

[Pekka Paalanen]

Hi all,

I thought I'd share this with you, so you can start experimenting with
the presentation feedback extension. The Weston branch at
http://cgit.collabora.com/git/user/pq/weston.git/log/?h=presentation-RFCv2-feedback
implements the presentation feedback part and should be fully usable.
The queueing part is still stubbed out.

The protocol is the same as originally proposed in RFCv2 at
http://lists.freedesktop.org/archives/wayland-devel/2014-January/012988.html

The branch includes a new demo, weston-presentation-shm, which
pre-renders 60 frames, and then just cycles those, measuring the
timings. The animation speed is intentionally tied to the refresh rate.

This explains the print-out:
http://cgit.collabora.com/git/user/pq/weston.git/tree/clients/presentation-shm.c?h=presentation-RFCv2-feedback#n345
All timestamps are truncated to milliseconds, because that is what the
frame callback carries.

The new demo seems to claim, that while weston hits every vblank, the
latency from commit to presentation is almost 2 refresh periods. I did
not investigate why.

I guess this branch could already be merged into Weston, except the
exact style of the protocol interfaces is still undecided, and the spec
needs some fixes we have been talking about in the RFCv2 thread.


Thanks,
pq