There are three normal scheduling policies:
SCHED_IDLE. However, the
SCHED_IDLE policies are intended for very low priority jobs, and as such are of limited interest in a performance tuning guide.
The default scheduling policy. This policy uses the Completely Fair Scheduler (CFS) to provide fair access periods for all threads using this policy. CFS establishes a dynamic priority list partly based on the
niceness value of each process thread. (Refer to the Deployment Guide for more details about this parameter and the
/proc file system.) This gives users some indirect level of control over process priority, but the dynamic priority list can only be directly changed by the CFS.