Manual Pages  — GSCHED

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 existing 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.

# 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.