1.\"
2.\" Copyright (c) 1996 Joerg Wunsch
3.\"
4.\" All rights reserved.
5.\"
6.\" This program is free software.
7.\"
8.\" Redistribution and use in source and binary forms, with or without
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20.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
21.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27.\"
28.\" $FreeBSD: head/share/man/man7/clocks.7 79727 2001-07-14 19:41:16Z schweikh $
29.\" "
30.Dd April 1, 1996
31.Os
32.Dt CLOCKS 7
33.Sh NAME
34.Nm clocks
35.Nd various system timers
36.Sh SYNOPSIS
37.Fd #include <time.h>
38.Sh DESCRIPTION
39.Ql HZ
40is not part of the application interface in BSD.
41.Pp
42There are many different real and virtual (timekeeping) clocks with
43different frequencies:
44.Bl -bullet -offset XXX
45.It
46The scheduling clock. This is a real clock with frequency that
47happens to be 100. It isn't available to applications.
48.It
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102.Xr sysctl 3
103or by reading it from the header in the profiling data file.
104.It
105The mc14618a clock. This is a real clock with a nominal frequency of
10632768. It is divided down to give the statistic clock and the profiling
107clock. It isn't available to applications.
108.It
109The microseconds clock. This is a virtual clock with frequency
1101000000. It is used for most timekeeping in BSD and is exported
111to applications in
112.Xr getrusage 2 ,
113.Xr gettimeofday 2 ,
114.Xr select 2 ,
115.Xr getitimer 2 ,
116etc... This is the clock that should normally be used
117by BSD applications.
118.It
119The i8254 clock. This is a real clock/timer with a nominal frequency of
1201193182. It is divided down to give the scheduling clock. It isn't
121available to applications.
122.It
123The TSC clock (64-bit register) on fifth-generation or later x86 systems.
124This is a real clock with a frequency that is equivalent to the number of
125cycles per second of the CPU(s).
--- 24 unchanged lines hidden ---
2.\" Copyright (c) 1996 Joerg Wunsch
3.\"
4.\" All rights reserved.
5.\"
6.\" This program is free software.
7.\"
8.\" Redistribution and use in source and binary forms, with or without
--- 11 unchanged lines hidden (view full) ---
20.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
21.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27.\"
28.\" $FreeBSD: head/share/man/man7/clocks.7 79727 2001-07-14 19:41:16Z schweikh $
29.\" "
30.Dd April 1, 1996
31.Os
32.Dt CLOCKS 7
33.Sh NAME
34.Nm clocks
35.Nd various system timers
36.Sh SYNOPSIS
37.Fd #include <time.h>
38.Sh DESCRIPTION
39.Ql HZ
40is not part of the application interface in BSD.
41.Pp
42There are many different real and virtual (timekeeping) clocks with
43different frequencies:
44.Bl -bullet -offset XXX
45.It
46The scheduling clock. This is a real clock with frequency that
47happens to be 100. It isn't available to applications.
48.It
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102.Xr sysctl 3
103or by reading it from the header in the profiling data file.
104.It
105The mc14618a clock. This is a real clock with a nominal frequency of
10632768. It is divided down to give the statistic clock and the profiling
107clock. It isn't available to applications.
108.It
109The microseconds clock. This is a virtual clock with frequency
1101000000. It is used for most timekeeping in BSD and is exported
111to applications in
112.Xr getrusage 2 ,
113.Xr gettimeofday 2 ,
114.Xr select 2 ,
115.Xr getitimer 2 ,
116etc... This is the clock that should normally be used
117by BSD applications.
118.It
119The i8254 clock. This is a real clock/timer with a nominal frequency of
1201193182. It is divided down to give the scheduling clock. It isn't
121available to applications.
122.It
123The TSC clock (64-bit register) on fifth-generation or later x86 systems.
124This is a real clock with a frequency that is equivalent to the number of
125cycles per second of the CPU(s).
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