Scheduling criteria is also called as scheduling methodology. Key to multiprogramming is scheduling. Different CPU scheduling algorithm have different properties .The criteria used for comparing these algorithms include the following:

  • CPU Utilization:

Keep the CPU as busy as possible. It range from 0 to 100%. In practice, it range from 40 to 90%.

  • Throughput:

Throughput is the rate at which processes are completed per unit of time.

  • Turnaround time:

This is the how long a process takes to execute a process. It is calculated as the time gap between the submission of a process and its completion.

  • Waiting time:

Waiting time is the sum of the time periods spent in waiting in the ready queue.

  • Response time:

Response time is the time it takes to start responding from submission time. It is calculated as the amount of time it takes from when a request was submitted until the first response is produced.

  • Fairness:

Each process should have a fair share of CPU.

Scheduling Algorithm Goals

  • All Systems:

  • Fairness:- Fair share of CPU to every process
  • Policy Enforcement: Stated policy is implemented properly
  • Balance: Keeping all resources equally busy

  • Batch System:

  • Throughput:- Maximize jobs per unit time
  • Turnaround Time:- Minimization of time between submission and termination
  • CPU Utilization:- Keep CPU busy all the time

  • Interactive System:

  • Response Time:- Quick response to request
  • Proportionality:- Meet user’s expectation

  • Real Time System:

  • Meeting Deadlines:- Avoiding losing data
  • Predictability:- Avoid quality degradation