Mesa Radeon Vulkan Driver Sees ~30% Performance Boost For APUs
The change by Feral's Alex Smith puts the uncached GTT type at a higher index than the visible vRAM type for these configurations without dedicated vRAM, namely APUs.
This fix boosted the average frame-rate for the Rise of the Tomb Raider Linux port by around 30% and other Feral Vulkan-powered Linux games as well as other titles.
The good news is due to the significant boost to performance and its high exposure, this "fix" to the RADV driver is marked as a candidate for back-porting to the Mesa 19.2 series rather than needing to wait until next quarter's Mesa 19.3.
Or if you are building your own Mesa, it's just a dozen line patch yielding the double digit Vulkan driver performance improvements.