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SCHED_4BSD(4)		     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  gen-
	     erate  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 config-
	     ured 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 in-
     ception 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 con-
     figurations, such as hyper-threading.

FreeBSD 15.1			January 21, 2008		   SCHED_4BSD(4)

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