except it doesn't really tell you much, because having some parts of CPUs underutilized doesn't mean adding load will utilize them. Like if load underutilizes floating point units and you have nothing else that uses them

> Like if load underutilizes floating point units

This is why I sigh really hard when people talk about some measurement of FLOPS per second, as if it's the only thing that matters.

It matters. Perhaps it matters a lot for specific workloads. But most general workloads are integer-based.

Also there's dark silicon to consider – the CPU simply cannot for thermal reasons run power to all parts of itself at the same time.