Somewhat like a Skiplist, which is introduced in a 1990 paper: http://en.wikipedia.org/wiki/Skip_list http://en.wikipedia.org/wiki/Skip_list I'm certain that

Somewhat like a Skiplist, which is introduced in a 1990 paper: http://en.wikipedia.org/wiki/Skip_list http://en.wikipedia.org/wiki/Skip_list I'm certain that at least one older algorithms text I own mentions skiplists, and there is no doubt much other prior art here, seems like the kind of thing that might find its way into kernel scheduling queues.