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

[From: Hämäläinen Kimmo]

On Fri, 2010-08-20 at 12:12 +0200, Tamminen Eero (Nokia-MS/Helsinki)
wrote:
> 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).

I'd say for non-composited you can get 33 FPS at maximum.  For
composited, 24 FPS if you are lucky.

-Kimmo

> 
> 
> 	- Eero
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