Section 3: Process Scheduling - bmitch26/Operating-Systems GitHub Wiki

Section 3. Process Scheduling

• CPU Scheduling
  • The way in which an OS decides which task gets to use the CPU Source
• Preemptive vs. Non-Preemptive Scheduling
  • Preemptive lets a process be booted from the running queue before it is finished, whereas Non-Preemptive waits for the processes to finish as needed. Source
• Scheduling Algorithms: Source
  • First-Come, First-Served (FCFS)
    • The prcoesses are taken in order of which ones request the CPU first.
  • Shortest Job Next (SJN)
    • Selects the waiting process that has the shortest execution time next.
  • Priority Scheduling
    • Preemptive method that works on the most important priority processes first.
  • Round Robin (RR)
    • Preemptive method where each process is cycled through with a fixed time slot (quantum).
  • Shortest Remaining Time (SRT)
    • Preemptive version of SJN
  • Multi-Level Queue Scheduling
    • Processes are divided into different classes of priority with their own scheduling needs. Processes cannot move between queues.
  • Multi-Level Feedback Queue Scheduling
    • Similar to Multi-Level Queue Scheduling, but the processes can move between queues.
  • Completely Fair Scheduler (CFS)
    • Divides the CPU time equally across all the processes based on Time Quantum/N, where N is the number of processes.