Scheduler Round-robin (RR) — divides execution into time slices (or quanta) with a given length . We maintain a queue of processes, but only execute each process for a maximum of time units at a time. If it’s still running, then we pre-empt and re-add to the back of the queue.

Performance depends on the quantum length Low too much context switching (adds overhead, not useful) High not enough switching. effectively reduces down to FCFS

RR has poor average waiting time when jobs have a similar length