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Diffstat (limited to 'sbin/geom/class/sched/gsched.8')
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diff --git a/sbin/geom/class/sched/gsched.8 b/sbin/geom/class/sched/gsched.8 new file mode 100644 index 0000000..bde84d0 --- /dev/null +++ b/sbin/geom/class/sched/gsched.8 @@ -0,0 +1,161 @@ +.\" Copyright (c) 2009-2010 Fabio Checconi, Luigi Rizzo +.\" All rights reserved. +.\" $FreeBSD$ +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.Dd April 12, 2010 +.Dt GSCHED 8 +.Os +.Sh NAME +.Nm gsched +.Nd "control utility for disk scheduler GEOM class" +.Sh SYNOPSIS +.Nm +.Cm create +.Op Fl v +.Op Fl a Ar algorithm +.Ar provider ... +.Nm +.Cm insert +.Op Fl v +.Op Fl a Ar algorithm +.Ar provider ... +.Nm +.Cm configure +.Op Fl v +.Op Fl a Ar algorithm +.Ar node ... +.Nm +.Cm destroy +.Op Fl fv +.Ar node ... +.Nm +.Cm reset +.Op Fl v +.Ar node ... +.Nm +.Cm { list | status | load | unload } +.Sh DESCRIPTION +The +.Nm +utility (also callable as +.Nm geom sched ... ) +changes the scheduling policy of the requests going to a provider. +.Pp +The first argument to +.Nm +indicates an action to be performed: +.Bl -tag -width ".Cm configure" +.It Cm create +Create a new provider and geom node using the specified scheduling algorithm. +.Ar algorithm +is the name of the scheduling algorithm used for the provider. +Available algorithms include: +.Ar rr , +which implements anticipatory scheduling with round robin service +among clients; +.Ar as , +which implements a simple form of anticipatory scheduling with +no per-client queue. +.Pp +If the operation succeeds, the new provider should appear with name +.Pa /dev/ Ns Ao Ar dev Ac Ns Pa .sched. . +The kernel module +.Pa geom_sched.ko +will be loaded if it is not loaded already. +.It Cm insert +Operates as "create", but the insertion is "transparent", +i.e. the existing provider is rerouted to the newly created geom, +which in turn forwards requests to the existing geom. +This operation allows one to start/stop a scheduling service +on an already existing provider. +.Pp +A subsequent 'destroy' will remove the newly created geom and +hook the provider back to the original geom. +.Ar algorithm +.It Cm configure +Configure existing scheduling provider. It supports the same options +as the +.Nm create +command. +.It Cm destroy +Destroy the geom specified in the parameter. +.It Cm reset +Do nothing. +.It Cm list | status | load | unload +See +.Xr geom 8 . +.El +.Pp +Additional options: +.Bl -tag -width ".Fl f" +.It Fl f +Force the removal of the specified provider. +.It Fl v +Be more verbose. +.El +.Sh SYSCTL VARIABLES +The following +.Xr sysctl 8 +variables can be used to control the behavior of the +.Nm SCHED +GEOM class. +The default value is shown next to each variable. +.Bl -tag -width indent +.It Va kern.geom.sched.debug : No 0 +Debug level of the +.Nm SCHED +GEOM class. +This can be set to a number between 0 and 2 inclusive. +If set to 0 minimal debug information is printed, and if set to 2 the +maximum amount of debug information is printed. +.El +.Sh EXIT STATUS +Exit status is 0 on success, and 1 if the command fails. +.Sh EXAMPLES +The following example shows how to create a scheduling provider for disk +.Pa /dev/da0 +, and how to destroy it. +.Bd -literal -offset indent +# Load the geom_sched module: +kldload geom_sched +# Load some scheduler classes used by geom_sched: +kldload gsched_rr gsched_as +# Configure device ad0 to use scheduler 'rr': +geom sched insert -s rr ad0 +# Now provider ad0 uses the 'rr' algorithm; +# the new geom is ad0.sched. +# Remove the scheduler on the device: +geom sched destroy -v ad0.sched. +.Ed +.Pp +.Sh SEE ALSO +.Xr geom 4 , +.Xr geom 8 +.Sh HISTORY +The +.Nm +utility appeared in April 2010. +.Sh AUTHORS +.An Fabio Checconi Aq fabio@FreeBSD.org +.An Luigi Rizzo Aq luigi@FreeBSD.org |