[maemo-developers] Horrible performance of GL rendering; why? (Qt, N900)

[From: Eero Tamminen]

Hi,

ext Robin Burchell wrote:
> Also note that pushing rotation updates every 10ms means you're trying to push 100fps
> (1000ms in a second, 1000/10 = 100), which is faster than the eye can percieve,
> and also faster than hardware can usually manage. 60fps is usually the upper
> bound, and anything over that is generally not going to be noticed except as
> additional burden on the system.

Yes, LCD is refreshed at ~60fps so anything over that is just stupid.
Trying to push more frames than the can actually go through the graphics
pipeline can support, can noticeably slow down / stall things.

If the app is non-fullscreen (= composited), the limit must be much
lower (at least down to 30fps), otherwise compositor won't even get
the boxed XDamage events for all the updates (X "boxes" them together).


	- Eero