1.\" $OpenBSD: microtime.9,v 1.6 2003/04/17 05:08:39 jmc Exp $ 2.\" $NetBSD: microtime.9,v 1.2 1999/03/16 00:40:47 garbled Exp $ 3.\" 4.\" Copyright (c) 1998 The NetBSD Foundation, Inc. 5.\" All rights reserved. 6.\" 7.\" This code is derived from software contributed to The NetBSD Foundation 8.\" by Jeremy Cooper. 9.\" 10.\" Redistribution and use in source and binary forms, with or without 11.\" modification, are permitted provided that the following conditions 12.\" are met: 13.\" 1. Redistributions of source code must retain the above copyright 14.\" notice, this list of conditions and the following disclaimer. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 3. All advertising materials mentioning features or use of this software 19.\" must display the following acknowledgement: 20.\" This product includes software developed by the NetBSD 21.\" Foundation, Inc. and its contributors. 22.\" 4. Neither the name of The NetBSD Foundation nor the names of its 23.\" contributors may be used to endorse or promote products derived 24.\" from this software without specific prior written permission. 25.\" 26.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36.\" POSSIBILITY OF SUCH DAMAGE. 37.\" 38.Dd September 14, 1998 39.Dt MICROTIME 9 40.Os 41.Sh NAME 42.Nm microtime 43.Nd realtime system clock 44.Sh SYNOPSIS 45.Fd #include <sys/time.h> 46.Ft void 47.Fo "microtime" 48.Fa "struct timeval *tv" 49.Fc 50.Sh DESCRIPTION 51.Fn microtime 52returns the current value of the system realtime clock in the structure 53pointed to by the argument 54.Fa tv . 55The system realtime clock is guaranteed to be monotonically increasing 56at all times. 57As such, 58all calls to 59.Fn microtime 60are guaranteed to return a system time greater than or equal to the 61system time returned in any previous calls. 62.Sh SEE ALSO 63.Xr settimeofday 2 , 64.Xr hardclock 9 , 65.Xr hz 9 , 66.Xr inittodr 9 , 67.Xr time 9 68.Sh CODE REFERENCES 69The implementation of the 70.Fn microtime 71function is machine dependent, 72hence its location in the source code tree varies from architecture to 73architecture. 74.Sh BUGS 75Despite the guarantee that the system realtime clock will always be 76monotonically increasing, 77it is always possible for the system clock to be manually reset by the 78system administrator to any date. 79