[jshap70]

> GPUs are generally black boxes that you throw code at.

umm... what? what does that even mean? lol

I could kind of maybe begin understand your argument from the Graphics side, as users mostly interact with it at an API level, however keep in mind that shaders are languages the same way "cpu languages" work. It's all still compiled to assembly, and there's no reason that you couldn't make an open instruction set for a GPU the same as a CPU. This is especially obvious when it comes to Compute workloads, as you're probably just writing "regular code".

Now, that said, would it be a good idea? I don't really see the benefit. A barebones GPU ISA would be too stripped back to do anything at all, and one with the specific accelerations needed to be useful will always want to be kept under wraps.

[kmeisthax]

Just 'cause Nvidia might want to keep architectural access under wraps doesn't necessarily mean that everyone else is going to, or that they have to in order to maintain a competitive advantage. CPU architectures are public knowledge, because people need to write compilers for them, and there are still all sorts of other barriers to entry and patent protections that would allow maintaining competitive advantage through new architectural innovations. This smells less of a competitive risk and more of a cultural problem.

I'm reminded of the argument over low-level graphics APIs almost a decade ago. AMD had worked together with DICE to write a new API for their graphics cards called Mantle, while Nvidia was pushing "AZDO" techniques about how to get the best performance out of existing OpenGL 4. Low-level APIs were supposed to be too complicated for graphics programmers for too little benefit. Nvidia's idea was that we just needed to get developers onto the OpenGL happy path and then all the CPU overhead of the API would melt away.

Of course, AMD's idea won, and pretty much every modern graphics API (DX12, Metal, WebGPU) provides low-level abstractions similar to how the hardware actually works. Hell, SPIR-V is already halfway to being a GPU ISA. The reason why OpenGL became such a high-overhead API was specifically because of this idea of "oh no, we can't tell you how the magic works". Actually getting all the performance out of the hardware became harder and harder because you were programming for a device model that was obsolete 10 years ago. Hell, things like explicit multi-GPU were just flat-out impossible. "Here's the tools to be high performance on our hardware" will always beat out "stay on our magic compiler's happy path" any day of the week.

[mhh__]

You could make a standardized GPU instruction set but why would anyone use it? We don't currently access GPUs at that level, like we do with the CPU.

It's technically possible but the economics isn't there (was my point). The cost of making a new GPU generally includes writing drivers and shader compilers anyway, so there's not much of a motivation to bother complying with a standard. It would be different if we did expose them at a lower level (i.e. if CPU were programmed with a jitted bytecode then we wouldn't see as much focus on ISA as long as the higher level semantics were preserved)