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Add time(9) to document the kernel time variables. Obtained from NetBSD and then modified by me to reflect some FreeBSD specific things and to clarify some other pointed based on some old mail from Bruce Evans about this man page.
1997-03-22 19:09:31 +00:00
.\" $NetBSD: time.9,v 1.1 1995/11/25 21:24:53 perry Exp $
.\"
.\" Copyright (c) 1994 Christopher G. Demetriou
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\" must display the following acknowledgement:
.\" This product includes software developed by Christopher G. Demetriou
.\" for the NetBSD Project.
.\" 3. The name of the author may not be used to endorse or promote products
.\" derived from this software without specific prior written permission
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
.\"
$Id$ -> $FreeBSD$
1999-08-28 00:22:10 +00:00
.\" $FreeBSD$
Add $Id$, to make it simpler for members of the translation teams to track. The $Id$ line is normally at the bottom of the main comment block in the man page, separated from the rest of the manpage by an empty comment, like so; .\" $Id$ .\" If the immediately preceding comment is a @(#) format ID marker than the the $Id$ will line up underneath it with no intervening blank lines. Otherwise, an additional blank line is inserted. Approved by: bde
1999-07-12 21:02:10 +00:00
.\"
kern: clarify boot time In FreeBSD, the current time is computed from uptime + boottime. Uptime is a continuous, smooth function that's monotonically increasing. To effect changes to the current time, boottime is adjusted. boottime is mutable and shouldn't be cached against future need. Document the current implementation, with the caveat that we may stop stepping boottime on resume in the future and will step uptime instead (noted in the commit message, but not in the code). Sponsored by: Netflix Reviewed by: phk, rpokala Differential Revision: https://reviews.freebsd.org/D30116
2021-05-05 18:32:13 +00:00
.Dd May 4, 2021
Add time(9) to document the kernel time variables. Obtained from NetBSD and then modified by me to reflect some FreeBSD specific things and to clarify some other pointed based on some old mail from Bruce Evans about this man page.
1997-03-22 19:09:31 +00:00
.Dt TIME 9
mdoc(7) police: removed HISTORY info from the .Os call.
2001-07-10 15:31:11 +00:00
.Os
Add time(9) to document the kernel time variables. Obtained from NetBSD and then modified by me to reflect some FreeBSD specific things and to clarify some other pointed based on some old mail from Bruce Evans about this man page.
1997-03-22 19:09:31 +00:00
.Sh NAME
.Nm boottime ,
Bring kernel time variable and access function docs up to date by updating the list of variables and mentioning the bin(up)time functions.
2004-09-17 07:24:18 +00:00
.Nm time_second ,
.Nm time_uptime
Add time(9) to document the kernel time variables. Obtained from NetBSD and then modified by me to reflect some FreeBSD specific things and to clarify some other pointed based on some old mail from Bruce Evans about this man page.
1997-03-22 19:09:31 +00:00
.Nd system time variables
.Sh SYNOPSIS
Scheduled mdoc(7) sweep.
2005-01-12 21:48:25 +00:00
.In sys/time.h
.Pp
.Vt extern struct timeval boottime ;
Fix types of time_second and time_uptime variables.
2006-03-02 19:47:41 +00:00
.Vt extern time_t time_second ;
.Vt extern time_t time_uptime ;
Add time(9) to document the kernel time variables. Obtained from NetBSD and then modified by me to reflect some FreeBSD specific things and to clarify some other pointed based on some old mail from Bruce Evans about this man page.
1997-03-22 19:09:31 +00:00
.Sh DESCRIPTION
The
.Va boottime
kern: clarify boot time In FreeBSD, the current time is computed from uptime + boottime. Uptime is a continuous, smooth function that's monotonically increasing. To effect changes to the current time, boottime is adjusted. boottime is mutable and shouldn't be cached against future need. Document the current implementation, with the caveat that we may stop stepping boottime on resume in the future and will step uptime instead (noted in the commit message, but not in the code). Sponsored by: Netflix Reviewed by: phk, rpokala Differential Revision: https://reviews.freebsd.org/D30116
2021-05-05 18:32:13 +00:00
variable holds the estimated system boot time.
This time is initially set when the system boots, either from the RTC, or from a
time estimated from the system's root filesystem.
When the current system time is set, stepped by
.Xr ntpd 8 ,
or a new time is read from the RTC as the system resumes,
.Va boottime
is recomputed as new_time - uptime.
The
.Xr sysctl 8
.Va kern.boottime
returns this value.
Add time(9) to document the kernel time variables. Obtained from NetBSD and then modified by me to reflect some FreeBSD specific things and to clarify some other pointed based on some old mail from Bruce Evans about this man page.
1997-03-22 19:09:31 +00:00
.Pp
The
Bring kernel time variable and access function docs up to date by updating the list of variables and mentioning the bin(up)time functions.
2004-09-17 07:24:18 +00:00
.Va time_second
variable is the system's
.Dq wall time
clock to the second.
Add time(9) to document the kernel time variables. Obtained from NetBSD and then modified by me to reflect some FreeBSD specific things and to clarify some other pointed based on some old mail from Bruce Evans about this man page.
1997-03-22 19:09:31 +00:00
.Pp
The
Scheduled mdoc(7) sweep.
2005-01-12 21:48:25 +00:00
.Va time_uptime
variable is the number of seconds since boot.
Add time(9) to document the kernel time variables. Obtained from NetBSD and then modified by me to reflect some FreeBSD specific things and to clarify some other pointed based on some old mail from Bruce Evans about this man page.
1997-03-22 19:09:31 +00:00
.Pp
The
Fixed punctuation in xrefs.
2005-01-21 20:48:00 +00:00
.Xr bintime 9 ,
Bring kernel time variable and access function docs up to date by updating the list of variables and mentioning the bin(up)time functions.
2004-09-17 07:24:18 +00:00
.Xr getbintime 9 ,
.Xr microtime 9 ,
.Xr getmicrotime 9 ,
.Xr nanotime 9 ,
and
Scheduled mdoc(7) sweep.
2005-01-12 21:48:25 +00:00
.Xr getnanotime 9
Bring kernel time variable and access function docs up to date by updating the list of variables and mentioning the bin(up)time functions.
2004-09-17 07:24:18 +00:00
functions can be used to get the current time more accurately and in an
atomic manner.
Similarly, the
Fixed punctuation in xrefs.
2005-01-21 20:48:00 +00:00
.Xr binuptime 9 ,
Bring kernel time variable and access function docs up to date by updating the list of variables and mentioning the bin(up)time functions.
2004-09-17 07:24:18 +00:00
.Xr getbinuptime 9 ,
.Xr microuptime 9 ,
.Xr getmicrouptime 9 ,
.Xr nanouptime 9 ,
Add time(9) to document the kernel time variables. Obtained from NetBSD and then modified by me to reflect some FreeBSD specific things and to clarify some other pointed based on some old mail from Bruce Evans about this man page.
1997-03-22 19:09:31 +00:00
and
Scheduled mdoc(7) sweep.
2005-01-12 21:48:25 +00:00
.Xr getnanouptime 9
Bring kernel time variable and access function docs up to date by updating the list of variables and mentioning the bin(up)time functions.
2004-09-17 07:24:18 +00:00
functions can be used to get the time elapse since boot more accurately
and in an atomic manner.
The
.Va boottime
variable may be read and written without special precautions.
kern: clarify boot time In FreeBSD, the current time is computed from uptime + boottime. Uptime is a continuous, smooth function that's monotonically increasing. To effect changes to the current time, boottime is adjusted. boottime is mutable and shouldn't be cached against future need. Document the current implementation, with the caveat that we may stop stepping boottime on resume in the future and will step uptime instead (noted in the commit message, but not in the code). Sponsored by: Netflix Reviewed by: phk, rpokala Differential Revision: https://reviews.freebsd.org/D30116
2021-05-05 18:32:13 +00:00
It is adjusted when the phase of the system time changes.
Add time(9) to document the kernel time variables. Obtained from NetBSD and then modified by me to reflect some FreeBSD specific things and to clarify some other pointed based on some old mail from Bruce Evans about this man page.
1997-03-22 19:09:31 +00:00
.Sh SEE ALSO
Bring kernel time variable and access function docs up to date by updating the list of variables and mentioning the bin(up)time functions.
2004-09-17 07:24:18 +00:00
.Xr clock_settime 2 ,
.Xr ntp_adjtime 2 ,
Add time(9) to document the kernel time variables. Obtained from NetBSD and then modified by me to reflect some FreeBSD specific things and to clarify some other pointed based on some old mail from Bruce Evans about this man page.
1997-03-22 19:09:31 +00:00
.Xr settimeofday 2 ,
Assorted markup fixes and minor wordsmithing. Approved by: re
2005-06-15 13:31:23 +00:00
.Xr bintime 9 ,
.Xr binuptime 9 ,
Bring kernel time variable and access function docs up to date by updating the list of variables and mentioning the bin(up)time functions.
2004-09-17 07:24:18 +00:00
.Xr getbintime 9 ,
.Xr getbinuptime 9 ,
.Xr getmicrotime 9 ,
.Xr getmicrouptime 9 ,
.Xr getnanotime 9 ,
.Xr getnanouptime 9 ,
.Xr microtime 9 ,
.Xr microuptime 9 ,
Fixed punctuation in xrefs.
2005-01-21 20:48:00 +00:00
.Xr nanotime 9 ,
Bring kernel time variable and access function docs up to date by updating the list of variables and mentioning the bin(up)time functions.
2004-09-17 07:24:18 +00:00
.Xr nanouptime 9
.Rs
.%A "Poul-Henning Kamp"
.%T "Timecounters: Efficient and precise timekeeping in SMP kernels"
Scheduled mdoc(7) sweep.
2005-01-12 21:48:25 +00:00
.%J "Proceedings of EuroBSDCon 2002, Amsterdam"
Bring kernel time variable and access function docs up to date by updating the list of variables and mentioning the bin(up)time functions.
2004-09-17 07:24:18 +00:00
.%O /usr/share/doc/papers/timecounter.ascii.gz
.Re
.Rs
.%A "Marshall Kirk McKusick"
.%A "George V. Neville-Neil"
.%B "The Design and Implementation of the FreeBSD Operating System"
.%D "July 2004"
.%I "Addison-Wesley"
.%P "57-61,65-66"
.Re
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