SCHED_RR doesn't limit CPU usage

Posted Sep 2, 2008 6:42 UTC (Tue) by simlo (guest, #10866)
In reply to: SCHED_FIFO and realtime throttling by jengelh
Parent article: SCHED_FIFO and realtime throttling

SCHED_RR is Round Robin _within_ the same priority. If there is no equal
priority task a SCHED_RR task is the same as a SCHED_FIFO task.

SCHED_RR doesn't limit CPU usage

Posted Sep 3, 2008 5:48 UTC (Wed) by jzbiciak (guest, #5246) [Link]

Are you saying SCHED_RR tasks don't get preempted at the end of their time quanta even if there's no other task ready at its level?

I guess it's only a minor point. I don't know if there are other housekeeping tasks the kernel can quickly dispatch of (CPU load balancing, for instance) if it periodically reschedules a SCHED_RR task, even if that prio level has only one task. Clearly, a running SCHED_RR task is the highest priority thing the CPU can and should run at that point.