It would be reasonable to expect doing nothing to be an easy, simple task for a kernel, but it isn’t. At Kernel Recipes 2018, Rafael Wysocki discussed what CPUs do when they don’t have anything to do, how the kernel handles this, problems inherent in the current strategy, and how his recent rework of the kernel’s idle loop has improved power consumption on systems that aren’t doing anything.
I had no idea doing nothing was this complex.
I think there was an episode of CppCast about embedded systems a while ago, about how making the microcontroller/cpu in microwave ovens slightly more efficient when idle could actually significantly reduce the carbon footprint of the US.
You clearly haven’t worked in an enterprise organisation. 😉