That’s different. Rendering happens entirely on the GPU, so the only data transfer is a one-way DMA stream containing scene primitives and instructions.
There's absolutely no reason it _has_ to be one-way: It's not like the CPU intrinsically speaks x86_64 or is directly attached to memory anyway. When inventing a new ISA we can do anything.
And if we're talking about memcpy over (small) ranges that are likely still in L1 you're definitely not going to notice the difference.
And if we're talking about memcpy over (small) ranges that are likely still in L1 you're definitely not going to notice the difference.