When supporting POSIX pthread scheduling as a scheduler type, round robin scheduling can be deferred until support for the FACE safety extended profile is desired. RMA and 653 do not have a time slicing policy. 

FACE Safety Base is unclear if SCHED_RR is a required scheduling policy. Since sched_rr_get_interval is only available in FACE safety extended and higher the initial offering is limited to SCHED_FIFO. In order to support round robin, the registry should specify the interval, and the ThreadAttributes_t defined in PCR 10177 will need to support the policy. The scheduling policy is set on a per thread basis, so when a thread with SCHED_FIFO policy is switched to the time slicing timer is effectively masked, and when a thread with SCHED_RR is switched to it is unmasked and reset to the interval. A context switch resulting from a window change should restore the time slice timer to the time remaining when the window was switched away from.  A new API or extension to getSystemInfoDEOS can expose the round robin interval. There is not an interface to change the interval.