1.\" Copyright (c) 2000 Kelly Yancey 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.\" $FreeBSD: src/share/man/man9/microtime.9,v 1.2.2.3 2001/12/17 11:30:18 ru Exp $ 26.\" $DragonFly: src/share/man/man9/microtime.9,v 1.4 2007/05/17 08:19:02 swildner Exp $ 27.\" 28.Dd January 3, 2000 29.Dt MICROTIME 9 30.Os 31.Sh NAME 32.Nm microtime , 33.Nm getmicrotime , 34.Nm nanotime , 35.Nm getnanotime 36.Nd get the current time 37.Sh SYNOPSIS 38.In sys/time.h 39.Ft void 40.Fn microtime "struct timeval *tv" 41.Ft void 42.Fn getmicrotime "struct timeval *tv" 43.Ft void 44.Fn nanotime "struct timespec *ts" 45.Ft void 46.Fn getnanotime "struct timespec *tsp" 47.Sh DESCRIPTION 48The 49.Fn microtime 50and 51.Fn getmicrotime 52functions stores the system time as a 53.Ft struct timeval 54at the address specified by 55.Fa tv . 56The 57.Fn nanotime 58and 59.Fn getnanotime 60functions perform the same utility, but record the time as a 61.Ft struct timespec 62instead. 63.Pp 64.Fn Microtime 65and 66.Fn nanotime 67always query the timecounter to return the current time as precisely as 68possible. 69Whereas 70.Fn getmicrotime 71and 72.Fn getnanotime 73functions are abstractions which can alternately return a less precise, but 74faster to obtain, time. 75This behaviour can be toggled via the 76kern.timecounter.method sysctl variable: 77.Bl -tag -width ABC 78.It Dv 0 79sacrifice precision in favor of faster code execution 80.It Dv 1 81return the more precise time (the same as calling 82.Fn microtime 83or 84.Fn nanotime ) . 85.El 86.Pp 87The intent of the 88.Fn getmicrotime 89and 90.Fn getnanotime 91functions is to enforce the user's preference for timer accuracy versus 92execution time. 93.Sh DIAGNOSTICS 94Buggy hardware can cause "calcru negative..." when kern.timecounter.method 95is set to 0. 96.Sh SEE ALSO 97.Xr getmicrouptime 9 , 98.Xr getnanouptime 9 , 99.Xr microuptime 9 , 100.Xr nanouptime 9 , 101.Xr tvtohz 9 102.Sh HISTORY 103The 104.Nm 105and 106.Nm nanotime 107functions first appeared in 108.Fx 3.0 109but existed in other incarnations since 110.Bx 4.4 111.Sh AUTHORS 112This manual page was written by 113.An Kelly Yancey Aq kbyanc@posi.net . 114