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: src/share/man/man9/ktr.9,v 1.8 2005/03/08 01:37:36 hmp Exp $ 26.\" $DragonFly: src/share/man/man9/ktr.9,v 1.5 2005/03/08 01:57:23 hmp Exp $ 27.\" 28.Dd February 15, 2001 29.Dt KTR 9 30.Os 31.Sh NAME 32.Nm CTR0 , CTR1 , CTR2 , CTR3 , CTR4 , CTR5 , CTR6 33.Nd kernel tracing facility 34.Sh SYNOPSIS 35.In sys/param.h 36.In sys/ktr.h 37.Vt "extern int ktr_cpumask" ; 38.Vt "extern int ktr_entries" ; 39.Vt "extern int ktr_extend" ; 40.Vt "extern int ktr_mask" ; 41.Vt "extern int ktr_verbose" ; 42.Vt "extern struct ktr_entry ktr_buf[]" ; 43.Ft void 44.Fn CTR0 "u_int mask" "char *format" 45.Ft void 46.Fn CTR1 "u_int mask" "char *format" "arg1" 47.Ft void 48.Fn CTR2 "u_int mask" "char *format" "arg1" "arg2" 49.Ft void 50.Fn CTR3 "u_int mask" "char *format" "arg1" "arg2" "arg3" 51.Ft void 52.Fn CTR4 "u_int mask" "char *format" "arg1" "arg2" "arg3" "arg4" 53.Ft void 54.Fn CTR5 "u_int mask" "char *format" "arg1" "arg2" "arg3" "arg4" "arg5" 55.Ft void 56.Fn CTR6 "u_int mask" "char *format" "arg1" "arg2" "arg3" "arg4" "arg5" "arg6" 57.Sh DESCRIPTION 58KTR provides a circular buffer of events that can be logged in a 59.Xr printf 9 60style 61fashion. 62These events can then be dumped with 63.Xr ddb 4 , 64.Xr gdb 1 65or 66.Xr ktrdump 8 . 67.Pp 68Events are created and logged in the kernel via the 69.Dv CTR Ns Ar x 70macros. 71The first parameter is a mask of event types 72.Pq Dv KTR_* 73defined in 74.Aq Pa sys/ktr.h . 75The event will be logged only if any of the event types specified in 76.Fa mask 77are enabled in the global event mask stored in 78.Va ktr_mask . 79The 80.Fa format 81argument is a 82.Xr printf 9 83style format string used to build the text of the event log message. 84Following the 85.Fa format 86string are zero to five arguments referenced by 87.Fa format . 88Note that the different macros differ only in the number of arguments each 89one takes, as indicated by its name. 90Each event is logged with a timestamp in addition to the log message. 91.Pp 92The 93.Va ktr_entries 94variable contains the number of entries in the 95.Va ktr_buf 96array. 97These variables are mostly useful for post-mortem crash dump tools to locate 98the base of the circular trace buffer and its length. 99.Pp 100The 101.Va ktr_mask 102variable contains the run time mask of events to log. 103.Pp 104The CPU event mask is stored in the 105.Va ktr_cpumask 106variable. 107.Pp 108The 109.Va ktr_verbose 110variable stores the verbose flag that controls whether events are logged to 111the console in addition to the event buffer. 112.Sh EXAMPLES 113This example demonstrates the use of tracepoints at the 114.Dv KTR_PROC 115logging level. 116.Bd -literal -compact 117void 118mi_switch() 119{ 120 ... 121 /* 122 * Pick a new current process and record its start time. 123 */ 124 ... 125 CTR3(KTR_PROC, "mi_switch: old proc %p (pid %d, %s)", p, p->p_pid, 126 p->p_comm); 127 ... 128 cpu_switch(); 129 ... 130 CTR3(KTR_PROC, "mi_switch: new proc %p (pid %d, %s)", p, p->p_pid, 131 p->p_comm); 132 ... 133} 134.Ed 135.Sh SEE ALSO 136.Xr ktr 4 137.Sh HISTORY 138The KTR kernel tracing facility first appeared in 139.Bsx 3.0 140and was imported into 141.Fx 5.0 142and 143.Dx 1.1 . 144