Improve composition with multiple outputs
This is an overview task
Motivation
X11
- glxgears is not smooth on second monitor with higher refresh rate #11
- 100% cpu usage after tty switch only with composition #9
- Have Nvidia use events for composition instead of timer #27 (closed)
Wayland
- 100% cpu usage in standby with moving element #68 (closed)
Plan
Composite per output on the output's vblank event. That allows to drive outputs with different refresh rates according to their specific rates.
In Wayland we have the DRM flip event for that making it very clean. On X11 it is questionable if it is doable so in this case at least the presentation should be synced with the output that has the highest refresh rate.