.\"	$OpenBSD: microtime.9,v 1.14 2013/06/04 19:27:10 schwarze Exp $
.\"     $NetBSD: microtime.9,v 1.2 1999/03/16 00:40:47 garbled Exp $
.\"
.\" Copyright (c) 1998 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Jeremy Cooper.
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.\" modification, are permitted provided that the following conditions
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.Dd $Mdocdate: June 4 2013 $
.Dt MICROTIME 9
.Os
.Sh NAME
.Nm microtime ,
.Nm getmicrotime ,
.Nm microuptime ,
.Nm getmicrouptime ,
.Nm nanotime ,
.Nm getnanotime ,
.Nm nanouptime ,
.Nm getnanouptime ,
.Nm bintime ,
.Nm binuptime
.Nd system clock
.Sh SYNOPSIS
.In sys/time.h
.Ft void
.Fo "microtime"
.Fa "struct timeval *tv"
.Fc
.Ft void
.Fo "getmicrotime"
.Fa "struct timeval *tv"
.Fc
.Ft void
.Fo "microuptime"
.Fa "struct timeval *tv"
.Fc
.Ft void
.Fo "getmicrouptime"
.Fa "struct timeval *tv"
.Fc
.Ft void
.Fo "nanotime"
.Fa "struct timespec *tv"
.Fc
.Ft void
.Fo "getnanotime"
.Fa "struct timespec *tv"
.Fc
.Ft void
.Fo "nanouptime"
.Fa "struct timespec *tv"
.Fc
.Ft void
.Fo "getnanouptime"
.Fa "struct timespec *tv"
.Fc
.Ft void
.Fo "bintime"
.Fa "struct bintime *tv"
.Fc
.Ft void
.Fo "binuptime"
.Fa "struct bintime *tv"
.Fc
.Sh DESCRIPTION
This family of functions return the system clock in various different formats.
The functions with the "uptime" suffix return the monotonically increasing
time since boot.
The functions without "up" return UTC time.
The various formats for the result are specified with:
.Bl -tag -offset indent -width "micro"
.It bin
result in struct bintime containing seconds and 64-bit fractions of seconds.
.It nano
result in struct timespec containing seconds and nanoseconds
.It micro
result in struct timeval containing seconds and microseconds
.El
.Pp
The functions with the "get" prefix return a less precise result, but much
faster.
They should be used where a precision of 10 msec is acceptable and where
performance is critical.
The functions without the "get" prefix return the best timestamp that can
be produced in the given format.
.Sh CODE REFERENCES
The implementation of these functions is partly machine dependent, but
the bulk of the code is in the file
.Pa sys/kern/kern_clock.c .
.Sh SEE ALSO
.Xr settimeofday 2 ,
.Xr hardclock 9 ,
.Xr hz 9 ,
.Xr inittodr 9 ,
.Xr time 9