1.\" $NetBSD: hardclock.9,v 1.3 2010/03/25 15:17:38 jruoho Exp $ 2.\" 3.\" Copyright (c) 2001 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to The NetBSD Foundation 7.\" by Thomas Klausner. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 19.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 20.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 21.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 22.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 23.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 24.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 25.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 26.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 27.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28.\" POSSIBILITY OF SUCH DAMAGE. 29.\" 30.Dd March 25, 2010 31.Dt HARDCLOCK 9 32.Os 33.Sh NAME 34.Nm hardclock 35.Nd real-time timer 36.Sh SYNOPSIS 37.Ft void 38.Fn hardclock "int cnt" "int usermode" 39.Sh DESCRIPTION 40The 41.Fn hardclock 42function is called 43.Xr hz 9 44times per second. 45It implements the real-time system clock. 46The argument 47.Va cnt 48is the estimated number of ticks since the last call to 49.Fn hardclock . 50The argument 51.Va usermode 52is none-zero when 53.Fn hardclock 54is called from a user-mode context. 55.Pp 56.Fn hardclock 57may perform different tasks such as: 58.Bl -bullet -offset indent 59.It 60Run the current process's virtual and profile time (decrease the 61corresponding timers, if they are activated, and generate 62.Li SIGVTALRM 63or 64.Li SIGPROF , 65respectively). 66.It 67Increment the time-of-day, taking care of any 68.Xr ntpd 8 69or 70.Xr adjtime 2 71induced changes and leap seconds, as well as any necessary 72compensations to keep in sync with PPS signals or external clocks, if 73support for this is in the kernel (see 74.Xr options 4 ) . 75.It 76Schedule softclock interrupts ( 77.Xr swi 9 ) 78processing. 79.It 80Collect 81.Xr hwpmc 4 82statistics. 83.It 84Do device polling, when enabled. 85.It 86Implement software 87.Xr watchdog 9 88processing. 89.It 90Enqueue 91.Xr epoch 9 92processing. 93.El 94.Sh SEE ALSO 95.Xr adjtime 2 , 96.Xr ntp_adjtime 2 , 97.Xr signal 3 , 98.Xr ntpd 8 , 99.Xr callout 9 , 100.Xr hz 9 101