.\"     $NetBSD: microtime.9,v 1.12 2008/04/30 13:10:58 martin Exp $
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.\" Copyright (c) 1998 The NetBSD Foundation, Inc.
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.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Jeremy Cooper.
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.Dd September 14, 1998
.Dt MICROTIME 9
.Os
.Sh NAME
.Nm microtime
.Nd realtime system clock
.Sh SYNOPSIS
.In sys/time.h
.Ft void
.Fo "microtime"
.Fa "struct timeval *tv"
.Fc
.Sh DESCRIPTION
.Fn microtime
returns the current value of the system realtime clock in the structure
pointed to by the argument
.Fa tv .
The system realtime clock is guaranteed to be monotonically increasing
at all times.
As such,
all calls to
.Fn microtime
are guaranteed to return a system time greater than or equal to the
system time returned in any previous calls.
.Sh SEE ALSO
.Xr settimeofday 2 ,
.Xr hardclock 9 ,
.Xr hz 9 ,
.Xr inittodr 9 ,
.Xr time_second 9
.Sh CODE REFERENCES
The implementation of the
.Fn microtime
function is machine dependent,
hence its location in the source code tree varies from architecture to
architecture.
.Sh BUGS
Despite the guarantee that the system realtime clock will always be
monotonically increasing,
it is always possible for the system clock to be manually reset by the
system administrator to any date.