.\"	$OpenBSD: hardclock.9,v 1.4 2003/03/08 23:17:18 jmc Exp $
.\"
.\" Copyright (c) 2001 Kenneth R Westerback
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.Dd July 14, 2001
.Dt HARDCLOCK 9
.Os
.Sh NAME
.Nm hardclock
.Nd real-time system clock
.Sh SYNOPSIS
.Fd #include <sys/systm.h>
.Ft void
.Fo "hardclock"
.Fa "struct clockframe *frame"
.Fc
.Sh DESCRIPTION
.Fn hardclock
implements the real-time system clock, interrupting
.Xr hz 9
times a second.
The argument
.Fa frame
is an opaque, machine dependant structure that encapsulates the
previous machine state.
.Pp
.Fn hardclock
performs a variety of time related housekeeping tasks, such as
.Bl -bullet -offset indent
.It
If the current process has virtual or profiling interval
timers, update the timers and deliver appropriate signals.
.It
If there is no separate statistics clock, execute
.Fn statclock .
.It
Increment the time of day, implementing any adjustments requested by
.Xr adjtime 2
or required as a result of running a ntp daemon or other configured
external clock.
.It
Update the real-time timeout queue, calling
.Fn softclock
directly if the current interrupt priority is low enough.
.El
.Sh SEE ALSO
.Xr adjtime 2 ,
.Xr hz 9 ,
.Xr microtime 9 ,
.Xr spl 9 ,
.Xr time 9 ,
.Xr timeout 9
.Sh CODE REFERENCES
.Fn hardclock
is implemented in the file
.Pa sys/kern/kern_clock.c .