In the last post I said the fundamental axiom of OS behavior is that at any given time, exactly one and only one task is active on a CPU. But if there’s absolutely nothing to do, then what? It turns out that this situation is extremely common, and for most personal computers it’s actually the norm: an ocean of sleeping processes, all waiting on some condition to wake up, while nearly 100% of CPU t
![What does an idle CPU do?](https://cdn-ak-scissors.b.st-hatena.com/image/square/be91de0d9bfcb145b67f797d7f327f8295f06fe8/height=288;version=1;width=512/https%3A%2F%2Fmanybutfinite.com%2Fimg%2Fos%2Fidle.png)