[antipurist]

> Everything is always on. Power consumption is constant.

That was the case in ye olden days of single-core CPUs, but is it still true today?

I can easily imagine a computer that has one always-on core for kernel chores and hardware management, and a dozen dormant cores that wake up when userland tasks need those cycles, all running in hard real time. Or even better, a mix of real-time for UI & audio on some cores + non-time-bound jobs on others.

[Animats]

There's the problem of what does the power management, shut down, and start up of dormant parts of the CPU. If that steals cycles from the OS, it can interfere with real time processing.

There's no reason that CPUs couldn't be designed to avoid such interference, but don't expect to find that on x86. Not sure about ARM.