18. Understanding Process Scheduling Algorithms

pravjot

18. Understanding Process Scheduling Algorithms

What are the key differences between preemptive and non-preemptive scheduling algorithms in process management? Provide examples of scenarios where each might be used.

gaurav133232

The key differences between preemptive and non-preemptive scheduling algos are:-

Preemptive scheduling algorithm:-

In preemptive scheduling algorithm, the process is interrupted before the completion of process task.
Starvation occurs after adding a high priority process to the queue.
CPU utilization is high in preemptive scheduling.
Resources are allocated here for a limited time.

For example, suppose certain processes are running in a system where each process is allocated a specific time period of 10 ms, if a process takes more time than that, that process is preempted, and the next one is scheduled.

Non-preemptive scheduling algorithm:-

In a non-preemptive scheduling algorithm, a process is not interrupted until its task are finished.
CPU utilization is low.
The CPU does not allow other processes to utilize resources until one has completed execution.
Resources are allocated until the task is done.

For example, suppose there's certain process waiting to be executed, they will be executed in the first come first serve basis, and each process would be allowed to execute until it finishes its task despite its priority.

mdaliakbar

Process scheduling is
the activity of the process manager that handles the removal of the
running process from the CPU and the selection of another process based
on a particular strategy.

Process scheduling is an
essential part of a Multiprogramming operating system. Such operating
systems allow more than one process to be loaded into the executable
memory at a time and the loaded process shares the CPU using time multiplexing.

DIFRENCE BETWEEN Preemptive scheduling algorithm AND Non-preemptive scheduling algorithm

Preemptive scheduling algorithm

The resources are assigned to a process for a long time period.
Its process may be paused in the middle of the execution.
When a high-priority process continuously comes in the ready queue, a low-priority process can starve.
It is flexible.
It is cost associated.
It affects the design of the operating system kernel.
Its CPU utilization is very high.
Examples: Round Robin and Shortest Remaining Time First

Non-preemptive scheduling algorithm

Once resources are assigned to a process, they are held until it completes its burst period or changes to the waiting state.
When the processor starts the process execution, it must complete it
before executing the other process, and it may not be interrupted in the
middle.
When a high burst time process uses a CPU, another process with a shorter burst time can starve.
It is rigid.
It does not cost associated.
It doesn't affect the design of the OS kernel.
Its CPU utilization is very low.
FCFS and SJF are examples of non-preemptive scheduling.

18. Understanding Process Scheduling Algorithms

18. Understanding Process Scheduling Algorithms

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