Process Scheduling

• The objective of multiprogramming is to have some process running at all times, to maximize CPU utilization.
• With the CPU switching back and forth among the processes, the rate at which a process performs its computation will not be uniform and probably not even reproducible if the same processes are run again.
• The objective of time sharing is to switch the CPU among processes so frequently that users can interact with each program while it is running.
• To meet these objectives, the process scheduler selects an available process (possibly from a set of several available processes) for program execution on the CPU.
• For a single-processor system, there will never be more than one running process. If there are more processes, the rest will have to wait until the CPU is free and can be rescheduled.