For today GPU generation, we know a lot more about the hardware mechanism than for previous GPU generation, in particular thanks to the window open on this hardware by Cuda. But many hardware details are still hidden to the programmer, in particular mechanisms used for primitives rasterisation and fragments shading. As understanding how fragments are scheduled among the G80 processing units is a critical points for the research we do with Fabrice Neyret as part of my PhD, I wrote a small program allowing to investigate this point.
The probing tool I wrote is called The Froggy FragSniffer and can be downloaded here (see Readme for details):http://www.icare3d.org/FragSniffer/FragSniffer_0.2.zip
We also wrote a document that presents our motivations for this work, the experiments we made yet and the results and answers we get: http://www.icare3d.org/GPU/CN08
We hope this document will give you useful informations. We don’t want it to be closed and we want to make it evolve through new experiments and also thanks to exterior comments you can leave at the bottom of this page.