A Mesa Fix Lands To Take Care Of The R9 290 Issue, Intel/Radeon Performance Problems
The fix by Michel Dänzer is loader/dri3: Always use at least two back buffers. Michel commented on the simple change, "This can make a significant difference for performance with some extreme test cases such as vblank_mode=0 glxgears."
The commit fixes this reported Intel bug about performance changes. Besides glxgears being affected, Sandy Bridge and Broxton was hit and included regressions for GfxBench, SynMark, Lightsmark, GpuTest, and more.
The commit also appears to take care of the R9 290 issue. For those unfamiliar with "the big R9 290 regression", see That Radeon Performance Regression For R9 290 Might Be Nailed. Great to see that the change in Mesa should be able to take care of this issue affecting recent versions of the Linux kernel.