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.\" 27.Dd January 3, 2000 28.Dt MICROTIME 9 29.Os 30.Sh NAME 31.Nm microtime , 32.Nm getmicrotime , 33.Nm nanotime , 34.Nm getnanotime 35.Nd get the current time 36.Sh SYNOPSIS 37.In sys/time.h 38.Ft void 39.Fn microtime "struct timeval *tv" 40.Ft void 41.Fn getmicrotime "struct timeval *tv" 42.Ft void 43.Fn nanotime "struct timespec *ts" 44.Ft void 45.Fn getnanotime "struct timespec *tsp" 46.Sh DESCRIPTION 47The 48.Fn microtime 49and 50.Fn getmicrotime 51functions stores the system time as a 52.Ft struct timeval 53at the address specified by 54.Fa tv . 55The 56.Fn nanotime 57and 58.Fn getnanotime 59functions perform the same utility, but record the time as a 60.Ft struct timespec 61instead. 62.Pp 63.Fn Microtime 64and 65.Fn nanotime 66always query the timecounter to return the current time as precisely as 67possible. 68Whereas 69.Fn getmicrotime 70and 71.Fn getnanotime 72functions are abstractions which can alternately return a less precise, but 73faster to obtain, time. 74This behaviour can be toggled via the 75kern.timecounter.method sysctl variable: 76.Bl -tag -width ABC 77.It Dv 0 78sacrifice precision in favor of faster code execution 79.It Dv 1 80return the more precise time (the same as calling 81.Fn microtime 82or 83.Fn nanotime ) . 84.El 85.Pp 86The intent of the 87.Fn getmicrotime 88and 89.Fn getnanotime 90functions is to enforce the user's preference for timer accuracy versus 91execution time. 92.Sh DIAGNOSTICS 93Buggy hardware can cause "calcru negative..." when kern.timecounter.method 94is set to 0. 95.Sh SEE ALSO 96.Xr getmicrouptime 9 , 97.Xr getnanouptime 9 , 98.Xr microuptime 9 , 99.Xr nanouptime 9 , 100.Xr tvtohz 9 101.Sh HISTORY 102The 103.Nm 104and 105.Nm nanotime 106functions first appeared in 107.Fx 3.0 108but existed in other incarnations since 109.Bx 4.4 110.Sh AUTHORS 111This manual page was written by 112.An Kelly Yancey Aq Mt kbyanc@posi.net . 113