I just started playing around with Panda3d a couple of days ago, and my general impression is that it’s fantastic. The only problem I have is that I get second long stalls on every panda program i run, if I don’t set
With sync-video off, I get no stalls and a frame rate thats usually over 600 FPS. I have a decently powerfull Dell Inspirion 1420 with a Nvidia GeForce 8 Series graphics card running an admittedly outdated Ubuntu Gutsy Gibbon.
I’ve been wondering why sync-video isn’t working for me. With sync-video on, I tried setting my panda3d program to the “realtime” round-robin scheduler with the highest priority possible, and I niced the process down to the highest priority possible, There was no change. So, I doubt that it’s the scheduler.
Then I started looking at the engine code to see what the sync-video call actually did, so that I could see if I could find any Nvidia driver information about it. As far, as I can tell, sync-video only calls
which according to the documentation I looked at doesn’t actually try to sync your application with the screen refresh. It simply caps the application to update no more often than every 1 screen refresh.
It looks like the GLX calls to actually sync the video to the refresh rate are
glXGetVideoSyncSGI() and glXWaitVideoSyncSGI(), which I couldn’t find called anywhere. Granted, I haven’t dug too hard.
So my question is, does panda3d actually try to sync to the video refreshes when it’s using openGL, or is it just capped at them? Because it seems to me that glXWaitVideoSyncSGI() might be just the thing that’s needed to make sure my panda programs wake up, and don’t keep stalling for a second or more.
Of course, if this is only happening to me, and I’m using an older kernel, and nvidia driver, there’s not much point in changing things.
So, do other linux users need to run with sync-video off to avoid stutters and stalls?