high framerate but random skipping on local game (mac os x)

[matthewtoldme]

here's the deal. i keep a framerate between 200 and 500fps but it randomly drops every few seconds, skipping a few frames--what's the deal?
i've attached a recording of what i'm talking about. i changed the settings from default to minimal as far as i know (included in the recording) and still the same thing.

imac G5
2GHz
2GB
128MB video ram

THANK YOU FOR HELPING ME ANYBODY!

[Z-Man]

Go to the menu "System Setup"/"Display Settings"/"Performance Tweaks" and set the swap mode to glFinish (please report back if you do that and it helps so we can make that the default for Mac+ATI). Or activate waiting for vsync, you don't get anything for your 500 fps anyway.

[matthewtoldme]

same problem with finish on. (glfinish is not an option, just finish) (recording included) i'm not sure what "waiting for vsync" is. i looked for it in the settings.

[Z-Man]

On VSYNC:
http://www.d-silence.com/feature.php?id=255
having it disabled is what gives you insanely high framerates. Your monitor can only display 60-100 frames per seconds, and enabling VSYNC will make your video card not generate more than your monitor can handle, which usually is a good idea.

You should be able to enable VSYNC somewhere in your display settings. I don't know where, sorry. It usually sits alongside options for antialiasing and anisotropic filtering.

You should also look for background processes eating up CPU time. In the Windows world, background virus scanners are often responsible for game slowdowns. For you, it may be that smart search thingie Apple recently introduced.

[Jonathan]

Spotlight works only on files, and it's event-based; i.e. it doesn't keep going over the entire file system all the time, unless it's a new install that hasn't been indexed yet. As long as there aren't many files that change it shouldn't be a problem. If it is a problem (I doubt it is with Armagetron) you can just put your stuff in an x.noindex directory, or add it to System Preferences -> Spotlight -> Privacy. I often do that when I write thousands of individual image files to put in some video.

Vsync: on Mac OS X there is only a standard way for programs to set it*. The default is always off. If you have an ATI GPU you can try ATI Displays, which lets you set vsync among some other things, per program. I prefer having vsync with, say, video, but with games I prefer not having it. It seems to make it smoother (and indeed it crams more time resolution into each frame in an awkward and ugly way (edit: not even that bad on a CRT), which also reduces average delay), and there are no abrupt drops to half the refresh rate when it can't keep up. Of course, you'll have to find out what works for you.

*

Code: Select all

CGLContextObj context = CGLCurrentContext(); /* or another */
long swapInterval = 1; /* supposedly minimum number of retraces per swap (synced if >0), but the last time I checked anything above 1 acted like 1 */
CGLSetParameter(context, kCGLCPSwapInterval, &swapInterval);