Several planners are available. This answer assumes the default schedulers: CFS (Linux) and ULE (FreeBSD).
CFS is short for a completely honest scheduler. The most notable difference is that CFS is not based on startup queues for process selection. Instead, it uses a red-black tree with O (log N) complexity, which is indexed by the CPU time spent.
Another notable detail: CFS uses nanoseconds to track time. From the Kernel :
CFS - jiffies HZ. , CFS "-" . :
/proc/sys/kernel/sched_granularity_ns
" " ( ) "" ( ) . . SCHED_BATCH CFS.
ULE BSD. SMP, . . , .
ULE CFS. ( ) CFS .
. kern.sched.interact ULE . CFS ULE .
ULE 3000 , CFS .