Re: Is it possible to have vsync with software rendering?

On Mon, 15 Sep 2014 16:42:21 +0000 (GMT)
Steven Stewart-Gallus <[email protected]> wrote:

> I wonder what the situation is
> like with Mesa on Wayland?

On Wayland, all presentation is always (if at all possible) vsynced in
the display server, and apps are expected to throttle themselves to the
display server's refresh rate. The Wayland core protocol supports this,
and apps are really expected to use it (wl_surface.frame).

Mesa's EGL throttles internally. As long as you have eglSwapInterval set
to 1 (the default), you should be getting properly throttled to the
display server refresh (the refresh rate of one output your window is
on, to be exact).

It would be nicer for the app if the app itself throttled, but Mesa can
very well do that for you, if you don't mind blocking inside Mesa.

To use software rendering with Mesa on Wayland, you need to be using
the egl_gallium EGL driver for the app, at least for now AFAIK.

(A Wayland display server is usually called a compositor.)


Thanks,
pq