mirror of
https://github.com/freebsd/freebsd-src
synced 2024-07-22 02:37:15 +00:00
195aa533c7
- Improve the wording that describes cnt and hz (avoid "the long haul") - Use .Fa for function arguments - Fix formatting of parenthesis around swi(9) xref - removed xref to non-existent options(4) - xref polling(4) - consistently list xrefs in SEE ALSO - xref eventtimers(9) in SEE ALSO Reviewed by: mav, rpokala MFC after: 1 week Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D39137
117 lines
3.1 KiB
Groff
117 lines
3.1 KiB
Groff
.\" $NetBSD: hardclock.9,v 1.3 2010/03/25 15:17:38 jruoho Exp $
|
|
.\"
|
|
.\" Copyright (c) 2001 The NetBSD Foundation, Inc.
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" This code is derived from software contributed to The NetBSD Foundation
|
|
.\" by Thomas Klausner.
|
|
.\"
|
|
.\" 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.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
|
|
.\" ``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 FOUNDATION OR CONTRIBUTORS
|
|
.\" 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.
|
|
.\"
|
|
.Dd February 27, 2023
|
|
.Dt HARDCLOCK 9
|
|
.Os
|
|
.Sh NAME
|
|
.Nm hardclock
|
|
.Nd real-time timer
|
|
.Sh SYNOPSIS
|
|
.Ft void
|
|
.Fn hardclock "int cnt" "int usermode"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn hardclock
|
|
function is called periodically based on pending work.
|
|
The rate ranges from
|
|
.Va hz
|
|
times per second on a very busy system, to twice a second on an idle system.
|
|
The
|
|
.Fa cnt
|
|
argument reports an estimate of the number of ticks since the last call.
|
|
Over long timescales, the average sum of
|
|
.Fa cnt
|
|
over one second is
|
|
.Va hz .
|
|
See
|
|
.Xr hz 9
|
|
for important details over shorter time scales.
|
|
The
|
|
.Fa usermode
|
|
argument is non-zero when
|
|
.Fn hardclock
|
|
is called from an context that interrupted usermode execution.
|
|
.Pp
|
|
.Fn hardclock
|
|
may perform different tasks such as:
|
|
.Bl -bullet -offset indent
|
|
.It
|
|
Run the current process's virtual and profile time (decrease the
|
|
corresponding timers, if they are activated, and generate
|
|
.Li SIGVTALRM
|
|
or
|
|
.Li SIGPROF ,
|
|
respectively).
|
|
.It
|
|
Increment the time-of-day, taking care of any
|
|
.Xr ntpd 8
|
|
or
|
|
.Xr adjtime 2
|
|
induced changes and leap seconds, as well as any necessary
|
|
compensations to keep in sync with PPS signals or external clocks, if
|
|
supported by the kernel.
|
|
.It
|
|
Schedule softclock interrupts
|
|
.Po
|
|
.Xr swi 9
|
|
.Pc
|
|
processing.
|
|
.It
|
|
Collect
|
|
.Xr hwpmc 4
|
|
statistics.
|
|
.It
|
|
Do device polling, when enabled
|
|
.Po
|
|
see
|
|
.Xr polling 4
|
|
.Pc .
|
|
.It
|
|
Implement software
|
|
.Xr watchdog 9
|
|
processing.
|
|
.It
|
|
Enqueue
|
|
.Xr epoch 9
|
|
processing.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr adjtime 2 ,
|
|
.Xr ntp_adjtime 2 ,
|
|
.Xr signal 3 ,
|
|
.Xr hwpmc 4 ,
|
|
.Xr polling 4 ,
|
|
.Xr ntpd 8 ,
|
|
.Xr epoch 9 ,
|
|
.Xr eventtimers 9 ,
|
|
.Xr hz 9 ,
|
|
.Xr swi 9 ,
|
|
.Xr watchdog 9
|