Running OpenGL 4.1, DRI3 With Mesa Git On An AMD Cayman GPU

The Cayman GPU used for this round of testing was the Radeon HD 6950 but rather a FirePro V7900, the old workstation card with a "Cayman Pro GL" GPU and 2GB of GDDR5 video memory that's still available to this day and commanding a $700+ USD price for a brand new card.
The days when AMD used to send out (a lot of) review samples to Phoronix for Linux testing...
This Cayman graphics card was indeed able to advertise OpenGL 4.1 when upgrading to Mesa Git. For an easy experience, from an Ubuntu 15.10 install I just enabled the Padoka PPA that ships Mesa Git alongside LLVM SVN.
For this brief comparison, I compared the performance with stock Mesa (v11.0.2) to Mesa 11.2-devel Git and then finally Mesa 11.2-devel Git while manually enabling DRI3. In an article last month I was showing off the significant DRI2 vs. DRI3 performance.