At the beginning of the month I reported on a small patch to Mesa that resulted in a huge performance improvement for Intel Sandy Bridge graphics, but Intel's OSTC developers have bumped up the performance of the latest-generation graphics processors even more. With the LLC caching patch-set, which should be committed to the Linux 2.6.40 kernel (not the current 2.6.39 cycle), there are measurable OpenGL performance improvements.
The performance improvements earlier this month came in the form of an Intel Mesa driver fix in user-space, but this latest round of optimizations land in the Intel Direct Rendering Manager code within the Linux kernel by introducing LLC caching for Sandy Bridge. I talked about the LLC caching patches a week ago when Chris Wilson posted fifteen patches for it, but on Tuesday Eric Anholt released a condense set of the work that's actually ready to be merged; that comes down to six patches. The patches in question can currently be found on the intel-gfx mailing list while they should officially land in time for the Linux 2.6.40 kernel when the next merge window opens. In posting the patches, Eric reports a roughly 20% performance improvement for OpenArena and 12% performance improvement for Nexuiz.
In this article there are benchmarks of the mainline Linux 2.6.38 and Linux 2.6.39-rc1 kernels then with the Linux 2.6.39-rc1 kernel plus the set of six LLC caching patches. The user-space side (Mesa 7.11-devel and xf86-video-intel) were maintained the same throughout testing and were pulled from Git on 30 March. Testing was done on the same system and with both Intel Core i5 2500K and Intel Core i3 2100 CPUs.
The i3-2100 and i5-2500K were running with an Intel H67 motherboard, 2GB of system memory, and 60GB OCZ Vertex 2 SSD. While the graphics stack was updated, this was on an Ubuntu 10.10 x86_64 base operating system. Tests included the usual OpenArena, Nexuiz, Warsow, World of Padman, Urban Terror, VDrift, and Lightsmark games that are known to work with the Intel Mesa driver on the Phoronix Test Suite.