— 4.4BSD scheduler
scheduler is the traditional system scheduler,
providing both high throughput and solid interactive response in the presence
The following sysctls are relevant to the operation of
- This read-only sysctl reports the name of the active
- This read-write sysctl reports or sets the length of the
quantum (in micro-seconds) granted to a thread.
- 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.
- 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.
scheduler has been present, in various forms,
since the inception of BSD
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.