124 lines
3.3 KiB
Groff
124 lines
3.3 KiB
Groff
.\" Copyright (c) 2015 Mark Johnston <markj@FreeBSD.org>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd April 18, 2015
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.Dt DTRACE_IO 4
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.Os
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.Sh NAME
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.Nm dtrace_io
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.Nd a DTrace provider for tracing events related to disk I/O
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.Sh SYNOPSIS
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.Fn io:::start "struct bio *" "struct devstat *"
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.Fn io:::done "struct bio *" "struct devstat *"
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.Sh DESCRIPTION
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The
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.Nm io
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provider allows the tracing of disk I/O events.
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The
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.Fn io:::start
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probe fires when a I/O request is about to be sent to the backing driver of a
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.Xr disk 9
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object.
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This occurs after all
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.Xr GEOM 4
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transformations have been performed on the request.
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The
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.Fn io:::done
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probe fires when a I/O request is completed.
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Both probes take a
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.Vt "struct bio *"
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representing the I/O request as their first argument.
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The second argument is a
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.Vt "struct devstat *"
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for the underlying
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.Xr disk 9
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object.
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.Sh ARGUMENTS
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The fields of
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.Vt "struct bio"
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are described in the
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.Xr g_bio 9
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manual page, and the fields of
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.Vt "struct devstat"
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are described in the
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.Xr devstat 9
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manual page.
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Translators for the
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.Vt bufinfo_t
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and
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.Vt devinfo_t
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D types are defined in
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.Pa /usr/lib/dtrace/io.d .
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.Sh FILES
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.Bl -tag -width "/usr/lib/dtrace/io.d" -compact
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.It Pa /usr/lib/dtrace/io.d
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DTrace type and translator definitions for the
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.Nm io
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provider.
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.El
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.Sh EXAMPLES
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The following script shows a per-process breakdown of total I/O by disk device:
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.Bd -literal -offset indent
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#pragma D option quiet
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io:::start
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{
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@[args[1]->device_name, execname, pid] = sum(args[0]->bio_bcount);
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}
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END
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{
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printf("%10s %20s %10s %15s\n", "DEVICE", "APP", "PID", "BYTES");
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printa("%10s %20s %10d %15@d\n", @);
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}
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.Ed
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.Sh COMPATIBILITY
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This provider is not compatible with the
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.Nm io
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provider found in Solaris, as its probes use native
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.Fx
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argument types.
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.Sh SEE ALSO
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.Xr dtrace 1 ,
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.Xr devstat 9 ,
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.Xr SDT 9
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.Sh HISTORY
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The
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.Nm io
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provider first appeared in
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.Fx
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9.2 and 10.0.
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.Sh AUTHORS
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This manual page was written by
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.An Mark Johnston Aq Mt markj@FreeBSD.org .
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.Sh BUGS
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The
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.Fn io:::wait-start
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and
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.Fn io:::wait-done
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probes are not currently implemented on
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.Fx .
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