GPU along with CPU rendering performance Blender 2.8 has a user preference of using GPU and CPU simultaneously during rendering. So, when a scene is getting rendered using this preference and 4 threads:


Is it true that during the beginning of render, GPU renders 1 tile and CPU cores render 3 tiles?
And also, suppose that near the end of render, 4 tiles remain to render. GPU starts rendering a tile and CPU cores start rendering remaining 3. As GPU would finish its tile faster than CPU cores, will it become idle while CPU cores slowly finish their tiles? Or will it take control of another tile from a CPU core to finish rendering faster?
I have tested this by rendering BMW scene at 256*240 (with tile size 128*180). So:
 1. It is true that during the beginning of render, GPU renders 1 tile and CPU cores render 3 tiles according to MSI Afterburner, which shows 99% GPU usage.
 2. Near the end of render, GPU usage becomes 0% while CPU cores render remaining 3 tiles slowly.