1.\" Copyright (c) 2015 Mark Johnston <markj@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.\" $FreeBSD$ 26.\" 27.Dd April 18, 2015 28.Dt DTRACE_IO 4 29.Os 30.Sh NAME 31.Nm dtrace_io 32.Nd a DTrace provider for tracing events related to disk I/O 33.Sh SYNOPSIS 34.Fn io:::start "struct bio *" "struct devstat *" 35.Fn io:::done "struct bio *" "struct devstat *" 36.Sh DESCRIPTION 37The 38.Nm io 39provider allows the tracing of disk I/O events. 40The 41.Fn io:::start 42probe fires when a I/O request is about to be sent to the backing driver of a 43.Xr disk 9 44object. 45This occurs after all 46.Xr GEOM 4 47transformations have been performed on the request. 48The 49.Fn io:::done 50probe fires when a I/O request is completed. 51Both probes take a 52.Vt "struct bio *" 53representing the I/O request as their first argument. 54The second argument is a 55.Vt "struct devstat *" 56for the underlying 57.Xr disk 9 58object. 59.Sh ARGUMENTS 60The fields of 61.Vt "struct bio" 62are described in the 63.Xr g_bio 9 64manual page, and the fields of 65.Vt "struct devstat" 66are described in the 67.Xr devstat 9 68manual page. 69Translators for the 70.Vt bufinfo_t 71and 72.Vt devinfo_t 73D types are defined in 74.Pa /usr/lib/dtrace/io.d . 75.Sh FILES 76.Bl -tag -width "/usr/lib/dtrace/io.d" -compact 77.It Pa /usr/lib/dtrace/io.d 78DTrace type and translator definitions for the 79.Nm io 80provider. 81.El 82.Sh EXAMPLES 83The following script shows a per-process breakdown of total I/O by disk device: 84.Bd -literal -offset indent 85#pragma D option quiet 86 87io:::start 88{ 89 @[args[1]->device_name, execname, pid] = sum(args[0]->bio_bcount); 90} 91 92END 93{ 94 printf("%10s %20s %10s %15s\n", "DEVICE", "APP", "PID", "BYTES"); 95 printa("%10s %20s %10d %15@d\n", @); 96} 97.Ed 98.Sh COMPATIBILITY 99This provider is not compatible with the 100.Nm io 101provider found in Solaris, as its probes use native 102.Fx 103argument types. 104.Sh SEE ALSO 105.Xr dtrace 1 , 106.Xr devstat 9 , 107.Xr SDT 9 108.Sh HISTORY 109The 110.Nm io 111provider first appeared in 112.Fx 1139.2 and 10.0. 114.Sh AUTHORS 115This manual page was written by 116.An Mark Johnston Aq Mt markj@FreeBSD.org . 117.Sh BUGS 118The 119.Fn io:::wait-start 120and 121.Fn io:::wait-done 122probes are not currently implemented on 123.Fx . 124