real-time system clock
implements the real-time system clock, interrupting
hz(9) times a second. The argument
frame is an opaque, machine dependent structure that
encapsulates the previous machine state.
performs a variety of time related housekeeping tasks, such as:
- If the current process has virtual or profiling interval timers, update
the timers and deliver appropriate signals.
- If there is no separate statistics clock, execute
- Increment the time of day, implementing any adjustments requested by
adjtime(2) or required as a result of
running an NTP daemon or other configured external clock.
- Update the real-time timeout queue, calling
directly if the current interrupt priority is low enough.
hardclock() is implemented in the file