While you're here, I should ask: what do you think of my middle-ground proposal (https://lobste.rs/s/oxzs1q/note_on_metal_shader_converter) that the interface contain a black-box scan primitive, rather than stronger low-level guarantees?
Out of scope for this blog post, but I also believe there is tremendous potential for hardware that broadly resembles existing GPUs (same register layout, instruction scheduling, memory hierarchy) but with fewer limitations and performance problems. For example, the queue that's currently hardcoded between vertex and fragment shaders could be exposed as a general purpose queue primitive, allowing more dynamic scheduling of multiple different kernels in parallel. I haven't done a deep enough dive into hardware to make concrete proposals, but as I explore, I get more and more indications that what we have access to is a fairly limited subset of what's possible.
And that's not even considering the vast differences between AMD and NV here. And then there are the mobile GPU constraints.
Still, would be fun to export more of the controls here. If you have access to a console devkit, some of these knobs are exposed.