Intel's Linux Graphics Driver Developers Discover 3~20% Boost For Current-Gen Hardware
Francisco Jerez, a longtime member of the Intel open-source Linux graphics team and former Nouveau contributor, landed patches he's been working on the past month to optimize slice/sub-slice load balancing behavior for Gen9 graphics. He discovered that the current behavior was sub-optimal and for the top-tier Gen9 GT4 (Iris Pro) graphics the performance problem is in particularly bad shape.
With Skylake GT4 graphics this tweaking of the slice/sub-slice load balancing behavior led up to around a 20% performance boost while in other cases was less severe but still noticeable like Unigine Valley running 3.4% faster, Gfxbench around 4%, some GpuTest scenes around 8%, and the SynMark tests yielding 15~22% boosts in performance.
The behavior change also helps the lower-tier Gen9 parts but to a lesser extent. Francisco is interested in hearing more feedback from performance testing with Intel hardware from Skylake through Whiskey Lake, Comet Lake, Amber Lake, and other Gen9-using generations.
Following that change to the i965 Mesa driver, Francisco also applied it to the Iris Gallium3D driver too, which is Intel's next-gen open-source OpenGL driver.
Just minutes ago this optimization was also ported to the Intel Vulkan (ANV) driver within Mesa but at least from the testing there is increasing performance by just ~3%.
These Intel Gen9 performance optimizations will be part of the Mesa 19.2 release that should be out by early September and found in the likes of Fedora 31 and Ubuntu 19.10. I'll be working on some fresh Intel Linux graphics benchmarks shortly.