First Come First Serve (FCFS)
•Also called first‐in first‐out (FIFO) –Jobs are scheduled in order of arrival to ready queue –“Real‐world” scheduling of people in lines (e.g., supermarket) –Typically non‐preemptive (no context switching at market) –Jobs treated equally, no starvation
FCFS Example
Problems with FCFS
•Average waiting time can be large if small jobs wait behind long ones (high turnaround time) –Non‐preemptive –You have a basket, but you’re stuck behind someone with a cart •Solution? –Express lane (12 items or less)
CS317 Operating