hardclock(9) – real-time system clock

HARDCLOCK(9) Kernel Developer's Manual HARDCLOCK(9)

NAME

hardclock — real-time system clock

SYNOPSIS

#include <sys/systm.h>

void
hardclock(struct clockframe *frame);

DESCRIPTION

hardclock() 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.

hardclock() 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 statclock().
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 softclock() directly if the current interrupt priority is low enough.

CODE REFERENCES

hardclock() is implemented in the file sys/kern/kern_clock.c.