b2d89ed701
- ad0 was referred to as da0 - wrong parameter -s instead of -a in example - use double quotes consistently PR: docs/150082 Submitted by: N.J. Mann <njm@njm.me.uk> MFC after: 2 weeks
164 lines
4.6 KiB
Groff
164 lines
4.6 KiB
Groff
.\" Copyright (c) 2009-2010 Fabio Checconi
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.\" Copyright (c) 2009-2010 Luigi Rizzo, Universita` di Pisa
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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 AUTHORS 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 AUTHORS 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 August 29, 2010
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.Dt GSCHED 8
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.Os
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.Sh NAME
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.Nm gsched
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.Nd "control utility for disk scheduler GEOM class"
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.Sh SYNOPSIS
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.Nm
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.Cm create
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.Op Fl v
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.Op Fl a Ar algorithm
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.Ar provider ...
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.Nm
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.Cm insert
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.Op Fl v
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.Op Fl a Ar algorithm
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.Ar provider ...
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.Nm
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.Cm configure
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.Op Fl v
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.Op Fl a Ar algorithm
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.Ar node ...
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.Nm
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.Cm destroy
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.Op Fl fv
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.Ar node ...
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.Nm
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.Cm reset
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.Op Fl v
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.Ar node ...
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.Nm
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.Cm { list | status | load | unload }
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.Sh DESCRIPTION
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The
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.Nm
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utility (also callable as
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.Nm geom sched ... )
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changes the scheduling policy of the requests going to a provider.
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.Pp
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The first argument to
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.Nm
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indicates an action to be performed:
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.Bl -tag -width ".Cm configure"
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.It Cm create
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Create a new provider and geom node using the specified scheduling algorithm.
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.Ar algorithm
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is the name of the scheduling algorithm used for the provider.
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Available algorithms include:
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.Ar rr ,
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which implements anticipatory scheduling with round robin service
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among clients;
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.Ar as ,
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which implements a simple form of anticipatory scheduling with
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no per-client queue.
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.Pp
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If the operation succeeds, the new provider should appear with name
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.Pa /dev/ Ns Ao Ar dev Ac Ns Pa .sched. .
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The kernel module
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.Pa geom_sched.ko
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will be loaded if it is not loaded already.
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.It Cm insert
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Operates as "create", but the insertion is "transparent",
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i.e. the existing provider is rerouted to the newly created geom,
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which in turn forwards requests to the existing geom.
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This operation allows one to start/stop a scheduling service
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on an already existing provider.
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.Pp
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A subsequent "destroy" will remove the newly created geom and
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hook the provider back to the original geom.
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.It Cm configure
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Configure existing scheduling provider. It supports the same options
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as the
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.Nm create
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command.
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.It Cm destroy
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Destroy the geom specified in the parameter.
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.It Cm reset
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Do nothing.
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.It Cm list | status | load | unload
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See
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.Xr geom 8 .
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.El
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.Pp
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Additional options:
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.Bl -tag -width ".Fl f"
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.It Fl f
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Force the removal of the specified provider.
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.It Fl v
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Be more verbose.
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.El
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.Sh SYSCTL VARIABLES
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The following
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.Xr sysctl 8
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variables can be used to control the behavior of the
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.Nm SCHED
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GEOM class.
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The default value is shown next to each variable.
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.Bl -tag -width indent
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.It Va kern.geom.sched.debug : No 0
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Debug level of the
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.Nm SCHED
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GEOM class.
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This can be set to a number between 0 and 2 inclusive.
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If set to 0 minimal debug information is printed, and if set to 2 the
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maximum amount of debug information is printed.
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.El
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.Sh EXIT STATUS
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Exit status is 0 on success, and 1 if the command fails.
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.Sh EXAMPLES
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The following example shows how to create a scheduling provider for disk
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.Pa /dev/ad0 ,
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and how to destroy it.
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.Bd -literal -offset indent
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# Load the geom_sched module:
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kldload geom_sched
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# Load some scheduler classes used by geom_sched:
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kldload gsched_rr gsched_as
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# Configure device ad0 to use scheduler "rr":
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geom sched insert -a rr ad0
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# Now provider ad0 uses the "rr" algorithm;
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# the new geom is ad0.sched.
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# Remove the scheduler on the device:
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geom sched destroy -v ad0.sched.
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.Ed
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.Pp
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.Sh SEE ALSO
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.Xr geom 4 ,
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.Xr geom 8
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.Sh HISTORY
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The
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.Nm
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utility first appeared in
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.Fx 8.1 .
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.Sh AUTHORS
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.An Fabio Checconi Aq fabio@FreeBSD.org
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.An Luigi Rizzo Aq luigi@FreeBSD.org
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