Accuracy of OpenGL ES Instrument
- by Rob Jones
I'm developing a game for the iPhone.  I've decided that 30FPS is plenty so I've written some code that only allows the App to present the render buffer every 1/30 of a second.  When I tried to verify this with Instruments I got varying information.
On an iPod Touch (2009 edition, 32G) it reports 30 FPS for Core Animation Frames Per Second.
On an iPhone 3G I get wildly varying results.  And not just less than 30 FPS.  I see 30 FPS on a regular basis.  It actually seems to hang closer to 36-39.
To investigate this anomaly I added my own FPS to the app and update it once per second.  I stays right at 29 FPS on both devices.
So, does anyone have any suggestions as to what might be going on?  I expect Instruments to be accurate so it really concerns me that it appears inaccurate.  It makes me think I have a bug somewhere, but I sure can't find it.