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SCHED_4BSD(4) FreeBSD Kernel Interfaces Manual SCHED_4BSD(4)
NAME
sched_4bsd - 4.4BSD scheduler
SYNOPSIS
options SCHED_4BSD
DESCRIPTION
The sched_4bsd scheduler is the traditional system scheduler, providing
both high throughput and solid interactive response in the presence of
load.
The following sysctls are relevant to the operation of sched_4bsd:
kern.sched.name
This read-only sysctl reports the name of the active scheduler.
kern.sched.quantum
This read-write sysctl reports or sets the length of the quantum
(in micro-seconds) granted to a thread.
kern.sched.ipiwakeup.enabled
This read-write sysctl sets whether or not the scheduler will
generate an inter-processor interrupt (IPI) to an idle CPU when a
thread is woken up. Otherwise, idle CPUs will wait until the
next clock tick before looking for new work.
kern.sched.preemption
This read-only sysctl reports whether or not the kernel is
configured to support preemption, which reduces the latency to
run lower priority threads on wakeup.
Some sysctls will be available only on systems supporting SMP.
SEE ALSO
sched_ule(4), sysctl(8)
HISTORY
The sched_4bsd scheduler has been present, in various forms, since the
inception of BSD.
BUGS
While a highly robust and time-tested scheduler, sched_4bsd lacks
specific knowledge of how to schedule advantageously in non-symmetric
processor configurations, such as hyper-threading.
FreeBSD 14.0-RELEASE-p11 January 21, 2008 FreeBSD 14.0-RELEASE-p11