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SCHED_4BSD(4) BSD Kernel Interfaces Manual SCHED_4BSD(4) NAME sched_4bsd -- 4.4BSD scheduler SYNOPSIS options SCHED_4BSD DESCRIPTION The sched_4bsd scheduler is the default 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 con- figured 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 spe- cific knowledge of how to schedule advantageously in non-symmetric pro- cessor configurations, such as hyper-threading. BSD April 7, 2005 BSD
NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | HISTORY | BUGS
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