gsched(8) [freebsd man page]
GSCHED(8) BSD System Manager's Manual GSCHED(8) NAME
gsched -- control utility for disk scheduler GEOM class SYNOPSIS
gsched create [-v] [-a algorithm] provider ... gsched insert [-v] [-a algorithm] provider ... gsched configure [-v] [-a algorithm] node ... gsched destroy [-fv] node ... gsched reset [-v] node ... gsched { list | status | load | unload } DESCRIPTION
The gsched utility (also callable as geom sched ...) changes the scheduling policy of the requests going to a provider. The first argument to gsched indicates an action to be performed: create Create a new provider and geom node using the specified scheduling algorithm. algorithm is the name of the scheduling algorithm used for the provider. Available algorithms include: rr, which implements anticipatory scheduling with round robin service among clients; as, which implements a simple form of anticipatory scheduling with no per-client queue. If the operation succeeds, the new provider should appear with name /dev/<dev>.sched.. The kernel module geom_sched.ko will be loaded if it is not loaded already. 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 exist- ing provider. A subsequent "destroy" will remove the newly created geom and hook the provider back to the original geom. configure Configure existing scheduling provider. It supports the same options as the create command. destroy Destroy the geom specified in the parameter. reset Do nothing. list | status | load | unload See geom(8). Additional options: -f Force the removal of the specified provider. -v Be more verbose. SYSCTL VARIABLES
The following sysctl(8) variables can be used to control the behavior of the SCHED GEOM class. The default value is shown next to each vari- able. kern.geom.sched.debug: 0 Debug level of the 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. EXIT STATUS
Exit status is 0 on success, and 1 if the command fails. EXAMPLES
The following example shows how to create a scheduling provider for disk /dev/ada0, and how to destroy it. # Load the geom_sched module: kldload geom_sched # Load some scheduler classes used by geom_sched: kldload gsched_rr # Configure device ada0 to use scheduler "rr": geom sched insert -a rr ada0 # Now provider ada0 uses the "rr" algorithm; # the new geom is ada0.sched. # Remove the scheduler on the device: geom sched destroy -v ada0.sched. SEE ALSO
geom(4), geom(8) HISTORY
The gsched utility first appeared in FreeBSD 8.1. AUTHORS
Fabio Checconi <fabio@FreeBSD.org> Luigi Rizzo <luigi@FreeBSD.org> BSD
July 26, 2012 BSD
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GNOP(8) BSD System Manager's Manual GNOP(8) NAME
gnop -- control utility for NOP GEOM class SYNOPSIS
gnop create [-v] [-e error] [-o offset] [-r rfailprob] [-s size] [-S secsize] [-w wfailprob] dev ... gnop configure [-v] [-e error] [-r rfailprob] [-w wfailprob] prov ... gnop destroy [-fv] prov ... gnop reset [-v] prov ... gnop list gnop status gnop load gnop unload DESCRIPTION
The gnop utility is used for setting up transparent providers on existing ones. Its main purpose is testing other GEOM classes, as it allows forced provider removal and I/O error simulation with a given probability. It also gathers the following statistics: number of read requests, number of write requests, number of bytes read and number of bytes written. In addition, it can be used as a good starting point for implementing new GEOM classes. The first argument to gnop indicates an action to be performed: create Set up a transparent provider on the given devices. If the operation succeeds, the new provider should appear with name /dev/<dev>.nop. The kernel module geom_nop.ko will be loaded if it is not loaded already. configure Configure existing transparent provider. At the moment it is only used for changing failure probability. destroy Turn off the given transparent providers. reset Reset statistics for the given transparent providers. list See geom(8). status See geom(8). load See geom(8). unload See geom(8). Additional options: -e error Specifies the error number to return on failure. -f Force the removal of the specified provider. -o offset Where to begin on the original provider. -r rfailprob Specifies read failure probability in percent. -s size Size of the transparent provider. -S secsize Sector size of the transparent provider. -w wfailprob Specifies write failure probability in percent. -v Be more verbose. SYSCTL VARIABLES
The following sysctl(8) variables can be used to control the behavior of the NOP GEOM class. The default value is shown next to each vari- able. kern.geom.nop.debug: 0 Debug level of the NOP GEOM class. This can be set to a number between 0 and 2 inclusive. If set to 0, minimal debug information is printed. If set to 1, basic debug information is logged along with the I/O requests that were returned as errors. If set to 2, the maximum amount of debug information is printed including all I/O requests. EXIT STATUS
Exit status is 0 on success, and 1 if the command fails. EXAMPLES
The following example shows how to create a transparent provider for disk /dev/da0 with 50% write failure probability, and how to destroy it. gnop create -v -w 50 da0 gnop destroy -v da0.nop The traffic statistics for the given transparent providers can be obtained with the list command. The example below shows the number of bytes written with newfs(8): gnop create da0 newfs /dev/da0.nop gnop list SEE ALSO
geom(4), geom(8) HISTORY
The gnop utility appeared in FreeBSD 5.3. AUTHORS
Pawel Jakub Dawidek <pjd@FreeBSD.org> BSD
April 14, 2013 BSD