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 1.7 2005/08/05 22:35:10 swildner Exp $ 27.\" 28.Dd February 15, 2001 29.Dt KTR 9 30.Os 31.Sh NAME 32.Nm CTR0 , 33.Nm CTR1 , 34.Nm CTR2 , 35.Nm CTR3 , 36.Nm CTR4 , 37.Nm CTR5 , 38.Nm CTR6 39.Nd kernel tracing facility 40.Sh SYNOPSIS 41.In sys/param.h 42.In sys/ktr.h 43.Vt "extern int ktr_cpumask" ; 44.Vt "extern int ktr_entries" ; 45.Vt "extern int ktr_extend" ; 46.Vt "extern int ktr_mask" ; 47.Vt "extern int ktr_verbose" ; 48.Vt "extern struct ktr_entry ktr_buf[]" ; 49.Ft void 50.Fn CTR0 "u_int mask" "char *format" 51.Ft void 52.Fn CTR1 "u_int mask" "char *format" "arg1" 53.Ft void 54.Fn CTR2 "u_int mask" "char *format" "arg1" "arg2" 55.Ft void 56.Fn CTR3 "u_int mask" "char *format" "arg1" "arg2" "arg3" 57.Ft void 58.Fn CTR4 "u_int mask" "char *format" "arg1" "arg2" "arg3" "arg4" 59.Ft void 60.Fn CTR5 "u_int mask" "char *format" "arg1" "arg2" "arg3" "arg4" "arg5" 61.Ft void 62.Fn CTR6 "u_int mask" "char *format" "arg1" "arg2" "arg3" "arg4" "arg5" "arg6" 63.Sh DESCRIPTION 64KTR provides a circular buffer of events that can be logged in a 65.Xr printf 9 66style 67fashion. 68These events can then be dumped with 69.Xr ddb 4 , 70.Xr gdb 1 71or 72.Xr ktrdump 8 . 73.Pp 74Events are created and logged in the kernel via the 75.Dv CTR Ns Ar x 76macros. 77The first parameter is a mask of event types 78.Pq Dv KTR_* 79defined in 80.Aq Pa sys/ktr.h . 81The event will be logged only if any of the event types specified in 82.Fa mask 83are enabled in the global event mask stored in 84.Va ktr_mask . 85The 86.Fa format 87argument is a 88.Xr printf 9 89style format string used to build the text of the event log message. 90Following the 91.Fa format 92string are zero to five arguments referenced by 93.Fa format . 94Note that the different macros differ only in the number of arguments each 95one takes, as indicated by its name. 96Each event is logged with a timestamp in addition to the log message. 97.Pp 98The 99.Va ktr_entries 100variable contains the number of entries in the 101.Va ktr_buf 102array. 103These variables are mostly useful for post-mortem crash dump tools to locate 104the base of the circular trace buffer and its length. 105.Pp 106The 107.Va ktr_mask 108variable contains the run time mask of events to log. 109.Pp 110The CPU event mask is stored in the 111.Va ktr_cpumask 112variable. 113.Pp 114The 115.Va ktr_verbose 116variable stores the verbose flag that controls whether events are logged to 117the console in addition to the event buffer. 118.Sh EXAMPLES 119This example demonstrates the use of tracepoints at the 120.Dv KTR_PROC 121logging level. 122.Bd -literal -compact 123void 124mi_switch() 125{ 126 ... 127 /* 128 * Pick a new current process and record its start time. 129 */ 130 ... 131 CTR3(KTR_PROC, "mi_switch: old proc %p (pid %d, %s)", p, p->p_pid, 132 p->p_comm); 133 ... 134 cpu_switch(); 135 ... 136 CTR3(KTR_PROC, "mi_switch: new proc %p (pid %d, %s)", p, p->p_pid, 137 p->p_comm); 138 ... 139} 140.Ed 141.Sh SEE ALSO 142.Xr ktr 4 143.Sh HISTORY 144The KTR kernel tracing facility first appeared in 145.Bsx 3.0 146and was imported into 147.Fx 5.0 148and 149.Dx 1.1 . 150