[Wayland-bugs] [Bug 763350] drawing performance worse than X

[gtk+ (GNOME Bugzilla)]

https://bugzilla.gnome.org/show_bug.cgi?id=763350

--- Comment #45 from Ray Strode [halfline] <rstrode at redhat.com> ---
(In reply to Christian Hergert from comment #40)
> I'm going to add some updated patches for cogl and mutter, but I'm
> unconvinced that we need them yet. Simply applying the gdk-wayland patch
> above gets us almost all the way there.
> 
> The reason I'm suggesting not using the cogl and mutter patches will be
> obvious by looking at the attached graph.
> 
> Notice how the predicted timing is 25msec across the board. This is what
> happens when GdkFrameClock can't predict the timing and so it guesses
> "half-way between frame". 16.7+8.35=25.5
So one thing I don't understand is, doesn't comment 37 / comment 38 imply the
timings aren't actually getting used at all? Granted, I haven't investigated in
detail with gdb/etc, but from your comment and briefly looking at the code it
seems like we freeze the clock any time we draw (on_frame_clock_after_paint),
and we thaw it when we get a frame callback.  As soon as we thaw it we call
maybe_start_idle which immediately dispatches the frame clock with a
min_interval of 0. I don't think the frame clock timings are used (or am I
missing something?)?

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