[Vm-dev] linux thread priorities

Andreas Raab andreas.raab at gmx.de
Thu Feb 4 05:56:52 UTC 2010

Igor Stasenko wrote:
> Wow.. 100ms? Sounds like you can't have more than 10 frames per
> second. Weird. Can it be because it waits for vsync?

No it's because it got stuff queued up that the GPU hasn't processed 
yet. SwapBuffers() forces it to process the pending stuff. What we've 
done to fix this is to issue a fence and a flush to let the GPU tell us 
when it's done processing without blocking. This brings the time in 
SwapBuffers() down but it requires that your GPU and drivers support the 
fence instructions (not all do; in particular Intel doesn't). I have no 
clue what the situation on Linux is but I expect the worst.

   - Andreas

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