Question

For Priority Scheduling,

• What is the arrival time, completion time, burst time, turnaround time, and the waiting time?
• discuss these terms further as they pertain to the efficiency of the algorithm as well as properties such as starvation.
• Pros and Cons of Priority Scheduling

Answer 1

hello,

let me define every point to you.

1. Arrival time: It is the time at which a process enters the ready queue.
2. Burst Time:   It is the total time needed to execute the particular process. It is different for Different types of process.
3. Turnaround Time:   It is the time difference between the arrival time of a process and the time of completion of that process.   turnaround Time= Completion time - arrival time
4. waiting time: It is the sum of total time for which the Process was waiting for CPU in ready Queue ., means , the process was in ready Queue but the CPU was not allocated to it,

So waiting time=Turnaround Time - Burst Time

In Priority Scheduling , The Scheduler only considers the Priority of process to assign CPU, So there is no overhead of burst Time and Arrival time.

The scheduling is completely based on priority , so it is easy to implement in operating system.

For a high Priority process, completion time , waiting time and turnaround time is small thus it increases the efficiency for high priority Process.

Starvation (in priority scheduling) is the Condition for a process when The Process is available in the ready Queue, But New Process of high priority Keep arriving in the ready Queue, because of which , a high priority process is unable to start and complete its execution, the process only resides in the ready queue but is unable to execute . This condition is called Starvation.

There are many Other advantages and Disadvantages of Priority Scheduling also:-

Advantages:-

• High Priority Process Does not need To wait for large duration of time.
• These Scheduling Method is very easy to implement.
• It has reasonable support of Priority.

Disadvantages:-

• Starvation for the low Priority Process.
• If Two Process have the same Priority then we have to decide for CPU allocation using another scheduling algorithm.
• If the system Fails, then all the Process which are having low Priority in ready queue would be lost.

I think i was able to solve your problem to a greater extent, feel free to post your queries in comment box.Please consider my efforts and upvote this solution.

Thanku:)