Is GPU memory wiped before it's handed to a new process, and is a process prevented from accessing GPU memory of a different process? (assuming low level APIs like Vulkan)
By the Vulkan spec it is guaranteed that memory from one process can't be seen by another. https://registry.khronos.org/vulkan/specs/1.3-extensions/htm... says: In particular, any guarantees made by an operating system about whether memory from one process can be visible to another process or not must not be violated by a Vulkan implementation for any memory allocation.
In theory you could have some sort of complex per-process scrambling system to avoid leaking information, but I think implementations actually just zero the memory.
GPU drivers on different operating systems can be more or less buggy; Windows and Linux generally seem to do the right thing, but MacOS is a bit more haphazard.
You can request Windows to zero out every GPU memory allocation, but it's more of a driver thing that's not exposed in APIs. Such option is likely to be off by default in drivers as it might induce additional, unintended overhead. In practice, you are likely to see memory cleared more often than not due to other reasons, though.
You can't just peek another process' GPU memory thru UMD app, either. Per-process virtual memory mechanisms similar to CPUs are also present in GPUs, which is the whole reason that resources are explicitly imported/exported across APIs via special API calls.
