Linux 5.16 is looking extremely promising for AMD Ryzen, at least for the APUs. In a recent comparison test conducted by Phoronix, the tested Ryzen APUs have shown up to a 28% performance boost over kernel 5.15. This 28% boost was captured in the Xonotic game at 4K resolution using low settings (image below). Other games and benchmarks have also shown significant improvements on Linux 5.16 in the range of around 10-20% on average.
This first set of tests was carried out on a Lenovo ThinkPad T14s Gen2 laptop with Ryzen 7 PRO 5850U. The 5850U is a Zen 3-based octa-core processor with 16 threads belonging to the AMD Cezanne APU lineup.
To see if the performance gain persisted on other Zen architectures, a Ryzen 5 5500U was also tested, and once again there is a significant performance boost to be had. The image below shows the improvements on the 5500U using Linux 5.16.
Although the Ryzen 5 5500U is a 5000 series mobile APU like the Ryzen 7 PRO 5850U, the former actually features Zen 2 cores and belongs to a different family dubbed "Lucienne".
Phoronix speculates the performance gain noted may be due to a combination of CPU-specific optimizations, among other things, for this kind of performance improvement. The site says:
This improvement with Linux 5.16 was fascinating and came unexpected. Linux 5.16 has many new features including AMDGPU kernel driver improvements, but this Radeon Vega graphics boost came as a surprise as there wasn't any announced optimization and the Vega graphics support at this stage is quite mature. It may also be a combination of CPU-related improvements with Linux 5.16.
It will be interesting to see if this type of result also holds true for the upcoming Rembrandt APUs.
Source and images: Phoronix