Query DXGI or whatever on linux once a frame to profile the VRAM usage and allocation capabilities is not a issue at all. Giving back the application the total - kernel - control of VRAM allocation means go back at least to Windows XP and let the system shot tons of BSODs for tons of reasons, from mindfucked users that filled the OS with crapware, to third party applications (rivatuner & co, I am speaking mostly about you!), to a bad code logic, to a lot totally legit actions and situation that even the best user cannot avoid or control, moreover it would totally break the the OS responsiveness and prevent toys like reshade to work at all. Finally you cannot guarantee allocation contiguity anyway. Programmes waited decades for page faulting on GPUs, what they really need and want is just a more efficient and faster page faulting mechanism.