* SKL or KBL device (don't have data from others)
* Ubuntu 18.04 / Unity
* drm-tip v4.19 or newer kernel
* git version of X with modifiers (dmabuf capable) enabled
* Mesa git version
* multithreading --fullscreen --benchmark --benchwarmup 3 --benchruntime 20
* FPS drops by 5-10%
Between following Mesa commits:
41c8f991379d1a 2018-11-12 18:28:04 util: Fix warning in u_cpu_detect on non-x86
25b48e3df93dee 2018-11-14 12:12:09 st/xa: Bump minor
Along with the perf drop, one can see both CPU & GPU power usage drops (according to RAPL), and GPU spending 30-40% in RC6 instead of 0%.
I.e. there's a Mesa change that makes this GPU test CPU bound.
I didn't see any significant perf changes in other benchmarks (Vulkan or GL).
There was some change between following commits:
* 2018-12-31 19:52:08 8c93ef5de9: radv: Do a cache flush if needed before reading predicates.
* 2019-01-02 18:09:04 7d6babf995: nir: add a way to print the deref chain
That changed the multithreading test perf:
* Fixed half of KBL-7 GT2 regression
* Fixed half of combined perf regression for SKL-i5 GT2, for the indicated interval, and another (as large) regression at end of November
* Improved perf a lot on BDW-3 GT2, much more than the small regression
GPU still spends significant time in RC6 (~20% on BDW-i3, 35-40% on SKL-i5, 45% on KBL-i7). CPU vs GPU power usage changes differ between platforms, but they're fairly small. All in all, pretty nice with clearly increased perf.