I’ve noticed that redering through opengl is very jerky under load. With software rendering it seems the scheduler can evenly distribute the load, but it fails to do so with opengl rendering. I’m using cfq scheduler with morph sources.
For example if I compile some stuff software rednering would be slow but it would be evenly slow (not jerky), GL rendering on the other hand would have stops on every few frames, it stutters. It doesn’t seem to be application specific.
Because you are not using glFinish() after each frame?
I’ve seen such jerky display in animations that generate frames based on gettimeofday() or similar. Inserting glFinish() at the end of the frame rendering solved the problem.