With xf86-video-modesetting continuing to add support for new features while being a generic hardware driver as long as there's an underlying DRM/KMS driver, how is the 2D and OpenGL performance compare when using this driver on an AMD GPU instead of the specialized xf86-video-ati DDX driver? Here's some benchmarks.

An independent user has uploaded some interesting benchmark results comparing the xf86-video-modesetting vs. xf86-video-ati DDX drivers on an openSUSE Tumbleweed system with Mesa 10.5-devel. A few 2D/XRENDER and OpenGL benchmarks were done -- all 2D operations are going through GLAMOR on both drivers given that it was a Radeon HD 7790 (GCN) GPU being benchmarked.

Those curious about the xf86-video-ati vs. xf86-video-modesetting performance can see this OpenBenchmarking.org result file. I don't have much more to add right now given that these were tests done independently by the community, but the results are interesting and worth sharing, and hopefully in the weeks ahead I'll find the time to do my own in-depth comparison of xf86-video-modesetting in its latest state against the various GPU-specific DDX drivers.