[PATCH 2/2] xwayland: Implement throttling for surfaces based on the frame event

[Adam Jackson]

On Mon, 2014-06-30 at 20:29 -0400, Jasper St. Pierre wrote:
> This implements simple throttling that keeps us to one attach per
> frame. There isn't really an active performance benefit, since the
> buffers will be redrawn only once per frame anyway, but it does cut down
> on the chatty network traffic. Since the Wayland sockets might fill
> up as well, the cut down on the volume of data we send out also provides
> us with a big stability benefit.
> 
> Namely, mutter is a lot more stable running gtkperf, a fairly intensive
> X11 application, after this change.

Not really, no.  Either with or without this change my gnome-on-wayland
session doesn't survive more than about three consecutive gtkperfs
before falling over.  (The difference between our scenarios, I suspect,
being that you have an extra moving part in that you're running mutter
--wayland under an existing X session where I'm running gnome-shell
--wayland _as_ my session.)

The issue with this patch, I think, is that instead of drowning the
wayland server with attaches, we're drowning it in create/destroy pairs
when gtkperf hits the popup tests.  Which means we actually want to
defer _all_ window surface activity to the frame event, so that when
popups live less than a frame time they never even reach xwayland.

- ajax