Operating System Scheduling by Hand: FCFS, Shortest Job First, Round Robin, Priorities, Page Replacement & Disk Scheduling

What you'll build

What you will be able to do

Each lab ends with a concrete result that you build yourself and the checker confirms, cell by cell.

• Take one finished run of six processes, calculate each process's turnaround and waiting time, the average waiting time and how busy the CPU really was.
• Schedule five jobs in arrival order, find start and completion times including an idle gap, calculate each job's waiting time and build a timeline that shows which job runs at every time unit.
• Rank six queued jobs by burst with a fair tie-break, list the bursts in shortest-first order, and compare the average waiting time with FCFS.
• Calculate start times under priority scheduling straight from the table with SUMIF, then apply a fictional ageing rule that lifts a starving job step by step to the top.
• Step four processes through round robin round by round, find how much CPU time each round uses, count the slices each process needs and see how a smaller quantum multiplies the context switches.
• Go through a reference string of twelve page requests with three frames, mark every hit and fault, count the faults, calculate the fault rate and confirm which frame FIFO loads at each fault.
• At one page fault you find when each page in memory was last used and when it will be needed next, pick the victim for LRU and for the optimal rule, and compare the fault counts – including FIFO's strange anomaly.
• Serve seven cylinder requests in three different orders, calculate the head movement of each step, build the elevator order with SMALL, check its total with a shortcut and compare the three methods in a chart.