Zircon Fair Scheduler

The fair scheduler, unlike O(1) scheduling disciplines such as priority round-robin (RR), uses an ordering criteria to compare and order threads in the run queue. As the current fair scheduler is based on WFQ, the finish time is used to select the position for the thread in the run queue relative to other threads. The Zircon fair scheduler instead uses the scheduling period as an idealized uniform time slice for the virtual timeline, because its value changes less dramatically.

Source: fuchsia.googlesource.com