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.\"    $FreeBSD: src/share/man/man9/microtime.9,v 1.2.2.3 2001/12/17 11:30:18 ru Exp $
.\"
.Dd September 23, 2017
.Dt MICROTIME 9
.Os
.Sh NAME
.Nm microtime ,
.Nm getmicrotime ,
.Nm nanotime ,
.Nm getnanotime
.Nd get the current time
.Sh SYNOPSIS
.In sys/time.h
.Ft void
.Fn microtime "struct timeval *tv"
.Ft void
.Fn getmicrotime "struct timeval *tv"
.Ft void
.Fn nanotime "struct timespec *ts"
.Ft void
.Fn getnanotime "struct timespec *tsp"
.Sh DESCRIPTION
The
.Fn microtime
and
.Fn getmicrotime
functions stores the system time as a
.Ft struct timeval
at the address specified by
.Fa tv .
The
.Fn nanotime
and
.Fn getnanotime
functions perform the same utility, but record the time as a
.Ft struct timespec
instead.
.Pp
.Fn Microtime
and
.Fn nanotime
always query the timecounter to return the current time as precisely as
possible.
Whereas
.Fn getmicrotime
and
.Fn getnanotime
functions are abstractions which return a less precise, but
faster to obtain, time.
The
.Fn getmicrouptime
and
.Fn getnanouptime
functions will return a time which is up to 1/HZ previous to the call.
.Pp
The intent of the
.Fn getmicrotime
and
.Fn getnanotime
functions is to enforce the user's preference for timer accuracy versus
execution time.
.Sh SEE ALSO
.Xr getmicrouptime 9 ,
.Xr getnanouptime 9 ,
.Xr microuptime 9 ,
.Xr nanouptime 9 ,
.Xr tvtohz 9
.Sh HISTORY
The
.Nm
and
.Nm nanotime
functions first appeared in
.Fx 3.0
but existed in other incarnations since
.Bx 4.4
.Sh AUTHORS
This manual page was written by
.An Kelly Yancey Aq Mt kbyanc@posi.net .