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/microuptime.9,v 1.2.2.2 2001/12/17 11:30:18 ru Exp $ 26.\" $DragonFly: src/share/man/man9/microuptime.9,v 1.3 2006/02/17 19:37:10 swildner Exp $ 27.\" 28.Dd January 3, 2000 29.Dt MICROUPTIME 9 30.Os 31.Sh NAME 32.Nm microuptime , 33.Nm getmicrouptime , 34.Nm nanouptime , 35.Nm getnanouptime 36.Nd get the time elapsed since boot 37.Sh SYNOPSIS 38.In sys/time.h 39.Ft void 40.Fn microuptime "struct timeval *tv" 41.Ft void 42.Fn getmicrouptime "struct timeval *tv" 43.Ft void 44.Fn nanouptime "struct timespec *ts" 45.Ft void 46.Fn getnanouptime "struct timespec *tsp" 47.Sh DESCRIPTION 48The 49.Fn microuptime 50and 51.Fn getmicrouptime 52functions store the time elapsed since boot as a 53.Ft struct timeval 54at the address specified by 55.Fa tv . 56The 57.Fn nanouptime 58and 59.Fn getnanouptime 60functions perform the same utility, but record the elapsed time as a 61.Ft struct timespec 62instead. 63.Pp 64.Fn Microuptime 65and 66.Fn nanouptime 67always query the timecounter to return the current time as precisely as 68possible. 69Whereas 70.Fn getmicrouptime 71and 72.Fn getnanouptime 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 microuptime 83or 84.Fn nanouptime ) . 85.El 86.Pp 87The intent of the 88.Fn getmicrouptime 89and 90.Fn getnanouptime 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 getmicrotime 9 , 98.Xr getnanotime 9 , 99.Xr microtime 9 , 100.Xr nanotime 9 , 101.Xr tvtohz 9 102.Sh AUTHORS 103This manual page was written by 104.An Kelly Yancey Aq kbyanc@posi.net . 105