I've seen and used solutions of user-level threads (aka green threads, aka coroutines) to do just that. It works. It's a lot of work to get right even for a ver

I've seen and used solutions of user-level threads (aka green threads, aka coroutines) to do just that. It works. It's a lot of work to get right even for a very specific use-case. In the past the power management on Linux was done by a user-space program, I'm not sure why that was changed.