Jason Ekstrand <ja...@jlekstrand.net> writes: > You don't have to continuously sync, just sync after every > attach/commit. While it may be somewhat non-obvious, I don't see how > calling sync once per frame is any worse than setting some flag > somewhere.
Hrmm thinking about it, I suppose sending the sync request isn't totally free because it will end up waking up the client an extra time to get the sync complete event. In a normal client this information wouldn't be used until the next time get_back_bo is called and Mesa's event queue is flushed so the wake up is not necessary. Waking up an extra time effectively negates the whole point of having the queuing mechanism in the first place. In this version 4 of the patch I made it so that it always does a sync request even if the application is using eglSwapInterval(1). This is needed because otherwise if the application isn't installing its own frame callback then it won't try to block for Mesa's frame callback until the next eglSwapInterval which means it won't have had a chance to receive any release events when get_back_bo is called. That would cause it to use an extra unnecessary buffer. So the patch effectively just turns off the queuing mechanism for all EGL clients through the backdoor. You could argue that we shouldn't use the sync request for eglSwapInterval(0) but I don't think that would be a good idea. The case where this would cause an extra redundant buffer is not a corner case. I think most game-style applications (eg, something using SDL) would hit this case because they would be relying on eglSwapInterval to do the throttling. I think making those games use an extra buffer is a worse crime than waking up the clients an extra time. The problem is not specific to the my patch and is happening right now with Weston master. I'm starting to wonder if we should just give up on the event queuing altogether. Regards, - Neil _______________________________________________ wayland-devel mailing list wayland-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/wayland-devel
