VRAM Allocation Issues

[shelter]

The reason why the game uses more memory in Linux is probably because of the graphics pipeline library used by Vulkan in dxvk/vkd3d-proton.

Regarding shared memory, I can only share what James said here

560 release feedback & discussion

The GPUs have been able to use onboard memory and system memory for most things interchangeably since roughly when we started shipping PCIe GPUs (GeForce 8600 was the first to have what I consider a fully unified memory subsystem, but some cards before that came pretty close as well). I’m not sure how your tool is calculating vidmem usage, but it’s possible it’s including some system memory used by the GPU as well.