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				.\" $NetBSD: hardclock.9,v 1.3 2010/03/25 15:17:38 jruoho Exp $
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				.Dd March 25, 2010
				.Dt HARDCLOCK 9
				.Os
				.Sh NAME
				.Nm hardclock
				.Nd real-time timer
				.Sh SYNOPSIS
				.Ft void
				.Fn hardclock "int cnt" "int usermode"
				.Sh DESCRIPTION
				mavUnsubmitted Done Inline Actions Why is it "fake" here, while referenced as "usermode" below? mav: Why is it "fake" here, while referenced as "usermode" below?
				impAuthorUnsubmitted Done Inline Actions because I was looking at the wrong function header and caught my mistake everywhere but here. imp: because I was looking at the wrong function header and caught my mistake everywhere but here.
				The
				.Fn hardclock
				function is called
				.Xr hz 9
				times per second.
				It implements the real-time system clock.
				The argument
				.Va cnt
				is the estimated number of ticks since the last call to
				.Fn hardclock .
				The argument
				.Va usermode
				is none-zero when
				.Fn hardclock
				is called from a user-mode context.
				.Pp
				.Fn hardclock
				may perform different tasks such as:
				.Bl -bullet -offset indent
				.It
				Run the current process's virtual and profile time (decrease the
				corresponding timers, if they are activated, and generate
				.Li SIGVTALRM
				or
				.Li SIGPROF ,
				respectively).
				.It
				Increment the time-of-day, taking care of any
				.Xr ntpd 8
				or
				.Xr adjtime 2
				induced changes and leap seconds, as well as any necessary
				compensations to keep in sync with PPS signals or external clocks, if
				support for this is in the kernel (see
				.Xr options 4 ) .
				.It
				Schedule softclock interrupts (
				.Xr swi 9 )
				processing.
				.It
				Collect
				.Xr hwpmc 4
				statistics.
				.It
				Do device polling, when enabled.
				.It
				Implement software
				.Xr watchdog 9
				processing.
				.It
				Enqueue
				.Xr epoch 9
				processing.
				.El
				.Sh SEE ALSO
				.Xr adjtime 2 ,
				.Xr ntp_adjtime 2 ,
				.Xr signal 3 ,
				.Xr ntpd 8 ,
				.Xr callout 9 ,
				.Xr hz 9