Hello, I have determined that my App is CPU bound due to API calls (DrawIndexedPrimitive) in particular. However, we have noticed a strange issue. In Fullscreen mode, we get a significant performance boost in that we seem to have a larger DrawPrimitive call budget. From the same viewpoint of the scene, we go from 20 fps to 30 fps. No additional optimization are going on in our app during the transition.
Can the drivers do more optimizations in fullscreen mode than windowed mode? Any possible explanation?
CPU API Bound Fullscreen Issue
I heard and even observed that in the past. I seriously hoped that would have gone away now so what you're describing is bad news. Could you please describe your test machine?
FS optimizations were the norm back in time, that's why D3D9 fullscreen mode requires to be explicitly marked (I know it isn't much different, but if you compare it to GL, it is). For "pure" D3D9 hardware there are probably good reasons for that, I seriously hope this is not happening on D3D10 HW.
If you're using desktop compositing, then consider you're likely paying some extra for that features, Vista used to be particularly hungry with that initially and it's probably still not optimal on some hardware/driver combinations.
Sorry but I don't know more, I hope that actually makes sense in your case.
FS optimizations were the norm back in time, that's why D3D9 fullscreen mode requires to be explicitly marked (I know it isn't much different, but if you compare it to GL, it is). For "pure" D3D9 hardware there are probably good reasons for that, I seriously hope this is not happening on D3D10 HW.
If you're using desktop compositing, then consider you're likely paying some extra for that features, Vista used to be particularly hungry with that initially and it's probably still not optimal on some hardware/driver combinations.
Sorry but I don't know more, I hope that actually makes sense in your case.
I usually see increased performance in fullscreen vs windowed mode (DX9,XP). I never really thought about it, but I always assumed that, in windowed mode, the desktop has to be checked for overlapping windows, etc., which would take at least a little time.
It's especially noticeable if you compare a maximized window vs fullscreen.
It's especially noticeable if you compare a maximized window vs fullscreen.
In vista, and possibly windows 7, microsoft automatically boosts the thread priority of a fullscreen app, compared to a windowed app. You should be able to get back some of the time by setting your thread priority higher.
see http://msdn.microsoft.com/en-us/library/ms686277%28v=vs.85%29.aspx
see http://msdn.microsoft.com/en-us/library/ms686277%28v=vs.85%29.aspx
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