Improving idle behavior in tickless systems

The code still doesn't and cannot predict device interrupts. That's something the article simply got wrong. Some part of it is based on the assumption that an idle state shouldn't be used if more than 4 of the last 8 measured idle periods were shorter than its so-called target residency. There doesn't seem to be any published rationale for this design and small powers of 2 always raise the suspicion of someone picking a number from a hat.

This may well be a sensible heuristic but a heuristic it remains --- no fortune telling aka "prediction" involved.