.\" $NetBSD: microuptime.9,v 1.12 2014/03/18 18:20:40 riastradh Exp $
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.\" Copyright (c) 2000 Kelly Yancey
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.\" $FreeBSD: src/share/man/man9/microuptime.9,v 1.7 2005/01/12 21:48:25 ru Exp $
.\"
.Dd June 8, 2010
.Dt MICROUPTIME 9
.Os
.Sh NAME
.Nm binuptime ,
.Nm getbinuptime ,
.Nm microuptime ,
.Nm getmicrouptime ,
.Nm nanouptime ,
.Nm getnanouptime
.Nd get the time elapsed since boot
.Sh SYNOPSIS
.In sys/time.h
.Ft void
.Fn binuptime "struct bintime *bt"
.Ft void
.Fn getbinuptime "struct bintime *bt"
.Ft void
.Fn microuptime "struct timeval *tv"
.Ft void
.Fn getmicrouptime "struct timeval *tv"
.Ft void
.Fn nanouptime "struct timespec *ts"
.Ft void
.Fn getnanouptime "struct timespec *tsp"
.Sh DESCRIPTION
The
.Fn binuptime
and
.Fn getbinuptime
functions store the time elapsed since boot as a
.Vt "struct bintime"
at the address specified by
.Fa bt .
The
.Fn microuptime
and
.Fn getmicrouptime
functions perform the same utility, but record the elapsed time as a
.Vt "struct timeval"
instead.
Similarly the
.Fn nanouptime
and
.Fn getnanouptime
functions store the elapsed time as a
.Vt "struct timespec" .
The used structures are described in
.Xr timeval 3 .
.Pp
The
.Fn binuptime ,
.Fn microuptime ,
and
.Fn nanouptime
functions
always query the timecounter to return the current time as precisely as
possible.
Whereas
.Fn getbinuptime ,
.Fn getmicrouptime ,
and
.Fn getnanouptime
functions are abstractions which return a less precise, but
faster to obtain, time.
.Pp
The intent of the
.Fn getbinuptime ,
.Fn getmicrouptime ,
and
.Fn getnanouptime
functions is to enforce the user's preference for timer accuracy versus
execution time.
They should be used where a precision of
.Pf 1/ Em HZ
(e.g., 10 msec on a
.Pf 100 Em HZ
machine, see
.Xr hz 9 )
is acceptable or where performance is priority.
.Sh SEE ALSO
.Xr microtime 9 ,
.Xr timecounter 9 ,
.Xr tvtohz 9
.Sh AUTHORS
This manual page was written by
.An Kelly Yancey Aq Mt kbyanc@posi.net .