Tuesday, August 25, 2009

Driver Thrash

I'm seeing a number of bug reports where weird artifacts are showing up in 940...missing pieces of runway, flickering triangles...all sorts of good stuff!

I believe that this is due to some kind of bug relating to threading, X-Plane and the video drivers. I won't say whose fault it is because I really don't know. I do know that the bug appears to not happen on OS X. (But this could simply be because the threads time out differently on OS X.)

The changes to the rendering engine for 940 from 930 are substantial and aggressive - it'll take us a little bit to fix these things.

When you wonder how come programs don't use all 8 of your cores yet, well...this is why...multi-core programming is complex, tricky, tedious to debug, and often involves substantial changes from the original code.


ikkarus said...

I'm seeing the problem on OS X (10.6), that is weird triangles all over the place. The application then bombs. I'll try to get it to do it again and submit a full bug report. It seems to take a while for it to happen...

Good luck with ye olde bug hunt.

Benjamin Supnik said...


Interesting...the thrash is due to a bug in X-plane's GL code...so far it had only been reported on Windows. Please watch the release notes and file a bug if this is reported "fixed on Windows" but persists on 10.6.

Anonymous said...

Neat, I thought I was alone here... Those symptoms started for me when I upgraded to the latest Catalyst drivers (the ones with OpenGL 3.2 support). Not sure if it's related.

Anyway, I eventually found out that those bugs disappear (for the duration of current flying session) when I uncheck then check again the pixel shader option.