clockspeed — speed up or slow down the local clock, continuously
clockspeed
clockspeed resets the local UNIX clock every three seconds according to (1) an internal hardware counter on the central processing unit and (2) occasional real-time measurements from a reliable source.
clockspeed reads the real-time measurements from /usr/local/clockspeed/adjust, a FIFO which it creates and reads from.
Each real-time measurement must be a single 16-byte packet, expressed as a TAI64NA time adjustment to the local UNIX clock.
This is the output of programs such as taiclock(1) and sntpclock(1).
clockspeed does not place any limits on the possible adjustments. It is your responsibility to make sure that the measurements are reliable.
After two real-time measurements, clockspeed can figure out the number of real attoseconds per CPU tick.
It saves this number in TAI64NA format in /usr/local/clockspeed/etc/atto, overwriting /usr/local/clockspeed/etc/atto.tmp for reliability.
It reads /usr/local/clockspeed/etc/atto when it starts up again.
clockspeed must be run by root.