Priority-based, preemptive scheduling with no timeslicing. This is equivalent
to what is called "manual round-robin" scheduling.
SCHED_RR
Priority-based, preemptive scheduling with timeslicing. Time quantums are
maintained on a per-thread basis and are not reset at each context switch.
Thus, a thread which is preempted and subsequently resumes execution will
attempt to complete the unused portion of its time quantum.
SCHED_OTHER
Priority-based, preemptive scheduling with timeslicing. Time quantums are
maintained on a per-thread basis and are reset at each context switch.
SCHED_SPORADIC
Priority-based, preemptive scheduling utilizing three additional parameters:
budget, replenishment period, and low priority. Under this policy, the
thread is allowed to execute for "budget" amount of time before its priority
is lowered to "low priority". At the end of each replenishment period,
the thread resumes its initial priority and has its budget replenished.
RTEMS POSIX API User's Guide