OpenGL performance degrade

Posts: 32
Joined: 2008.10
Post: #1
I've been monitoring the behaviour of my game, and noticed a performance degradation as I swap textures in and out of the iPhone. When the game originally starts, I get a solid 56-58 frames per second, and as the user restarts the game multiple times the frame rate starts dropping 2-3 frames every restart.

I dynamically reload all menu and game textures. All resources are dilligently monitored, so for every generate there is a corresponding delete, and all instruments I've used (both Apple based ones, nVidia PerfKit for Windows desktop, and even my own monitors and counters which interogate OpenGL state) show that there are NO leaks in my game code/engine. Shark happily reports the GART Resident & Wired Object size always match the acquire/release cycles, and end up with the same amount of commited texture memory after each cycle. There is 100% no resource leak in my code.

Shark does report an increase in Renderer Utilization - every game restart cycle increases this number by 3-5%. Correspondingly, the Tiler Utilization also increases around 3-5% every cycle. This is obviously where my frame rate is being consumed. Interestingly enough, the scene counter stays the same, as does commited texture memory (only the in/out addresses are different).

Has anyone else noticed this performance degradation with constant texture swapping? I do not have the luxury of loading all textures upfront, ie. I must dynamically swap textures for various levels of the game, as well as the menu system.

Any suggestions?
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Posts: 1,487
Joined: 2002.09
Post: #2
Memory fragmentation perhaps?

Scott Lembcke - Howling Moon Software
Author of Chipmunk Physics - A fast and simple rigid body physics library in C.
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