You can create metrics for whatever you want! Go ahead!

But cuda is not a black box math accelerator. You can stupidly treat it as such, but that doesn’t make it that. It’s an entire ecosystem with drivers and contexts and lifecycles. If everything you’re doing is synchronous and/or you don’t mind if your metrics include totally unrelated costs, then time.time() is fine, sure. But if that’s the case, you’ve got bigger problems.

Sure, it’s easy to say “there are bigger problems.” There are always bigger problems.

But, there are like 50 years worth of Fortran numerical codes out there, lots of them just use RCIs… if I want to try CUDA in some existing library, I guess I will need the vector back before I can go back into the RCI.

You're arguing with people who have no idea what they're talking about on a forum that is a circular "increase in acceleration" of a personality trait that gets co-opted into arguing incorrectly about everything - a trait that everyone else knows is defective.