ChorusOS 4.0 Introduction


A scheduler is a feature which provides scheduling policies. A scheduling policy is a set of rules, procedures, or criteria used in making processor scheduling decisions. Each scheduler feature implements one or more scheduling policies, interacting with the core executive according to a defined kernel internal interface. A scheduler is mandatory in all kernel instances. The core executive includes the default FIFO scheduler.

The default scheduler present in the core executive implements a CLASS_FIFO scheduling class, which provides simple pre-emptive scheduling based on thread priorities.

More detailed information about these scheduling classes is found in threadScheduler(2K).

For more details on scheduling, see SCHED(5FEA).


The optional ROUND_ROBIN scheduler feature enables the additional CLASS_RR scheduling class, which is similar to CLASS_FIFO but adds round-robin time slicing based on a configurable time quantum.

For more details, see ROUND_ROBIN(5FEA).