Last week after a modern Intel Gallium3D driver was proposed for mainline Mesa, a side discussion ended up being ignited about making the i915 Gallium3D driver the default for older generations of Intel graphics hardware. To see where the i915 Gallium3D driver is at compared to the i915 Classic Mesa DRI driver, here are some new benchmarks from aging Intel i945 hardware.
The i915 proposal -- and what looks like will end up happening -- is changing the default open-source Intel Linux graphics driver for old i915 through i945 IGPs (common to the first-generation Intel Atom netbooks) to be using the community-initiated Gallium3D driver rather than Intel's i915 classic Mesa driver. The oldest i8xx hardware would still be using the classic Mesa driver while the i965 hardware and newer (up to and including Sandy/Ivy Bridge and Haswell and Valley View) is using the i965 classic Mesa driver. The i915 Gallium3D driver started off as work by VMware (then Tungsten Graphics) and over the years has become quite a decent driver while Intel really doesn't do much to their classic i915 driver these days.
Google has significantly advanced the Gallium3D driver as they used it over "i915c" for some older Chromebooks with i945 graphics. They have managed decent performance and delivered new features over what's found in the classic i915 driver. This Gallium3D driver is a big win since it's much faster for software emulation of vertex shaders and other OpenGL features by leveraging LLVM to cover the graphics hardware's shortcomings. The i915 Gallium3D driver is in compliant with OpenGL 2.1 where as the official driver just supports OpenGL 1.4 for this old hardware.
For this morning's benchmarking, the i915 Gallium3D and i915 Classic Mesa performance was compared on an older Apple Mac Mini with an Intel Core 2 Duo T5600 processor and i945 integrated graphics. The system was running Ubuntu 13.04 with the Linux 3.8 kernel, Unity 7.0, xf86-video-intel 2.21.6, LLVM 3.2, and the Mesa revision tested was from Git master last week of Mesa 9.2.0 git-9fb5b2f.
All benchmarking was handled via the Phoronix Test Suite for this lax Intel graphics hardware to see how the Gallium3D and Mesa drivers compare.