[TUHS] The evolution of Unix facilities and architecture

[Jeremy C. Reed]

profil code somewhere in here?
https://github.com/weiss/original-bsd/commits/master/sys/kern/kern_clock.c?after=b44636d7febc9dcf553118bd320571864188351d+104

that has the sccs history back to April 1980 for src/sys/sys/clock.c