A big.LITTLE scheduler update

From what I can see, __stop_machine() was designed to simplify some of the synchronization issues surrounding CPU hotplug. As you say, there might be an analogy between __stop_machine() and the stop-the-world nature of some garbage collectors. That said, my personal guess is that a more-organized CPU-hotplug notification strategy will help quite a bit, and modifications to the way that CPUs are iterated over will help some more. In contrast, concurrent garbage collectors cannot assume much about the data that they collecting garbage from.

But we will see!