1.\" Copyright (c) 2001 John H. Baldwin <jhb@FreeBSD.org>
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: head/share/man/man9/ktr.9 147398 2005-06-15 13:31:23Z ru $
26.\"
27.Dd February 15, 2001
28.Dt KTR 9
29.Os
30.Sh NAME
31.Nm CTR0 , CTR1 , CTR2 , CTR3 , CTR4 , CTR5
32.Nd kernel tracing facility
33.Sh SYNOPSIS
34.In sys/param.h
35.In sys/ktr.h
36.Vt "extern int ktr_cpumask" ;
37.Vt "extern int ktr_entries" ;
38.Vt "extern int ktr_extend" ;
39.Vt "extern int ktr_mask" ;
40.Vt "extern int ktr_verbose" ;
41.Vt "extern struct ktr_entry ktr_buf[]" ;
42.Ft void
43.Fn CTR0 "u_int mask" "char *format"
44.Ft void
45.Fn CTR1 "u_int mask" "char *format" "arg1"
46.Ft void
47.Fn CTR2 "u_int mask" "char *format" "arg1" "arg2"
48.Ft void
49.Fn CTR3 "u_int mask" "char *format" "arg1" "arg2" "arg3"
50.Ft void
51.Fn CTR4 "u_int mask" "char *format" "arg1" "arg2" "arg3" "arg4"
52.Ft void
53.Fn CTR5 "u_int mask" "char *format" "arg1" "arg2" "arg3" "arg4" "arg5"
54.Sh DESCRIPTION
55KTR provides a circular buffer of events that can be logged in a
56.Xr printf 9
57style
58fashion.
59These events can then be dumped with
60.Xr ddb 4 ,
61.Xr gdb 1
62or
63.Xr ktrdump 8 .
64.Pp
65Events are created and logged in the kernel via the
66.Dv CTR Ns Ar x
67macros.
68The first parameter is a mask of event types
69.Pq Dv KTR_*
70defined in
71.In sys/ktr.h .
72The event will be logged only if any of the event types specified in
73.Fa mask
74are enabled in the global event mask stored in
75.Va ktr_mask .
76The
77.Fa format
78argument is a
79.Xr printf 9
80style format string used to build the text of the event log message.
81Following the
82.Fa format
83string are zero to five arguments referenced by
84.Fa format .
85Note that the different macros differ only in the number of arguments each
86one takes, as indicated by its name.
87Each event is logged with a timestamp in addition to the log message.
88.Pp
89The
90.Va ktr_entries
91variable contains the number of entries in the
92.Va ktr_buf
93array.
94These variables are mostly useful for post-mortem crash dump tools to locate
95the base of the circular trace buffer and its length.
96.Pp
97The
98.Va ktr_mask
99variable contains the run time mask of events to log.
100.Pp
101The CPU event mask is stored in the
102.Va ktr_cpumask
103variable.
104.Pp
105The
106.Va ktr_verbose
107variable stores the verbose flag that controls whether events are logged to
108the console in addition to the event buffer.
109.Sh EXAMPLES
110This example demonstrates the use of tracepoints at the
111.Dv KTR_PROC
112logging level.
113.Bd -literal
114void
115mi_switch()
116{
117 ...
118 /*
119 * Pick a new current process and record its start time.
120 */
121 ...
122 CTR3(KTR_PROC, "mi_switch: old proc %p (pid %d, %s)", p, p->p_pid,
123 p->p_comm);
124 ...
125 cpu_switch();
126 ...
127 CTR3(KTR_PROC, "mi_switch: new proc %p (pid %d, %s)", p, p->p_pid,
128 p->p_comm);
129 ...
130}
131.Ed
132.Sh SEE ALSO
133.Xr ktr 4 ,
134.Xr ktrdump 8
135.Sh HISTORY
136The KTR kernel tracing facility first appeared in
137.Bsx 3.0
138and was imported into
139.Fx 5.0 .
140.Sh BUGS
141Currently there is one global buffer shared among all CPUs.
142It might be profitable at some point in time to use per-CPU buffers instead
143so that if one CPU halts or starts spinning, then the log messages it
144emitted just prior to halting or spinning will not be drowned out by events
145from the other CPUs.
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: head/share/man/man9/ktr.9 147398 2005-06-15 13:31:23Z ru $
26.\"
27.Dd February 15, 2001
28.Dt KTR 9
29.Os
30.Sh NAME
31.Nm CTR0 , CTR1 , CTR2 , CTR3 , CTR4 , CTR5
32.Nd kernel tracing facility
33.Sh SYNOPSIS
34.In sys/param.h
35.In sys/ktr.h
36.Vt "extern int ktr_cpumask" ;
37.Vt "extern int ktr_entries" ;
38.Vt "extern int ktr_extend" ;
39.Vt "extern int ktr_mask" ;
40.Vt "extern int ktr_verbose" ;
41.Vt "extern struct ktr_entry ktr_buf[]" ;
42.Ft void
43.Fn CTR0 "u_int mask" "char *format"
44.Ft void
45.Fn CTR1 "u_int mask" "char *format" "arg1"
46.Ft void
47.Fn CTR2 "u_int mask" "char *format" "arg1" "arg2"
48.Ft void
49.Fn CTR3 "u_int mask" "char *format" "arg1" "arg2" "arg3"
50.Ft void
51.Fn CTR4 "u_int mask" "char *format" "arg1" "arg2" "arg3" "arg4"
52.Ft void
53.Fn CTR5 "u_int mask" "char *format" "arg1" "arg2" "arg3" "arg4" "arg5"
54.Sh DESCRIPTION
55KTR provides a circular buffer of events that can be logged in a
56.Xr printf 9
57style
58fashion.
59These events can then be dumped with
60.Xr ddb 4 ,
61.Xr gdb 1
62or
63.Xr ktrdump 8 .
64.Pp
65Events are created and logged in the kernel via the
66.Dv CTR Ns Ar x
67macros.
68The first parameter is a mask of event types
69.Pq Dv KTR_*
70defined in
71.In sys/ktr.h .
72The event will be logged only if any of the event types specified in
73.Fa mask
74are enabled in the global event mask stored in
75.Va ktr_mask .
76The
77.Fa format
78argument is a
79.Xr printf 9
80style format string used to build the text of the event log message.
81Following the
82.Fa format
83string are zero to five arguments referenced by
84.Fa format .
85Note that the different macros differ only in the number of arguments each
86one takes, as indicated by its name.
87Each event is logged with a timestamp in addition to the log message.
88.Pp
89The
90.Va ktr_entries
91variable contains the number of entries in the
92.Va ktr_buf
93array.
94These variables are mostly useful for post-mortem crash dump tools to locate
95the base of the circular trace buffer and its length.
96.Pp
97The
98.Va ktr_mask
99variable contains the run time mask of events to log.
100.Pp
101The CPU event mask is stored in the
102.Va ktr_cpumask
103variable.
104.Pp
105The
106.Va ktr_verbose
107variable stores the verbose flag that controls whether events are logged to
108the console in addition to the event buffer.
109.Sh EXAMPLES
110This example demonstrates the use of tracepoints at the
111.Dv KTR_PROC
112logging level.
113.Bd -literal
114void
115mi_switch()
116{
117 ...
118 /*
119 * Pick a new current process and record its start time.
120 */
121 ...
122 CTR3(KTR_PROC, "mi_switch: old proc %p (pid %d, %s)", p, p->p_pid,
123 p->p_comm);
124 ...
125 cpu_switch();
126 ...
127 CTR3(KTR_PROC, "mi_switch: new proc %p (pid %d, %s)", p, p->p_pid,
128 p->p_comm);
129 ...
130}
131.Ed
132.Sh SEE ALSO
133.Xr ktr 4 ,
134.Xr ktrdump 8
135.Sh HISTORY
136The KTR kernel tracing facility first appeared in
137.Bsx 3.0
138and was imported into
139.Fx 5.0 .
140.Sh BUGS
141Currently there is one global buffer shared among all CPUs.
142It might be profitable at some point in time to use per-CPU buffers instead
143so that if one CPU halts or starts spinning, then the log messages it
144emitted just prior to halting or spinning will not be drowned out by events
145from the other CPUs.