Scheduling Criteria

5.2 Scheduling Criteria

There are several different criteria to consider when trying to select the "best" scheduling algorithm
CPU utilization - Ideally the CPU would be busy 100% of the time, so as to waste 0 CPU cycles
Throughput - Number of processes completed per unit time.
Turnaround time - Time required for a particular process to complete,
Waiting time - How much time processes spend in the ready queue waiting their turn to get on the CPU
Response time - The time taken in an interactive program from the issuance of a command to the commence of a response to that command.


A nonpreemptive scheduling algorithm picks a process to run and then just lets it run until it blocks (either on I/O or waiting for another process) or until it voluntarily releases the CPU.
First-Come-First-Served (FCFS),
Shortest Job first (SJF).

a pre-emptive scheduling algorithm picks a process and lets it run for a maximum of some fixed time. If it is still running at the end of the time interval, it is suspended and the scheduler picks another process to run.
Round-Robin (RR),
Priority Scheduling.


http://www2.cs.uic.edu/~jbell/CourseNotes/OperatingSystems/5_CPU_Scheduling.html