I'm encountering increased CPU execution times when using Vulkan on an APU.
The issue occurs once a command buffer (empty or not) is submitted. After that, CPU computations seem to take around twice the time.
I modified the Vulkan SDK triangle demo (version 1.0.24) to reproduce the problem, only performing initialization and one submission, then measuring some spinning. (See this Gist)
More complex applications consistently behave the same.
- Carrizo (rev 4) APU
- Windows 7
- Radeon driver package 16.7.3
I could not reproduce similar behavior on other platforms.