CPU Scheduling Algorithms Simulation

This assignment explores CPU scheduling algorithms through a deterministic modeling system built in Java. It delves into different scheduling criteria such as arrival time, burst time, turnaround time, and waiting time. The implementation covers various algorithms like First Come First Served (FCFS), Shortest Job First (SJF), Priority-based, Round Robin (RR), Multilevel Queue, and Multilevel Feedback queuing. The system simulates job execution, handles input/output operations, and addresses challenges in accurately representing CPU burst durations and I/O time bursts.

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System for
Deterministic Modeling of
CPU Scheduling Algorithms
Author name

System for Deterministic Modeling of CPU Scheduling Algorithms 2
Techniques Used
Tools Used:
Eclipse: We have used eclipse IDE for the coding purpose.
Programming Language: Java
We have used java as the programming language to code these scheduling Algorithms
We have used Java Collections ArrayList to store the jobs, finished jobs and even for storing the
Jobs on IO devices, we have used ArrayList.

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All the important aspects
There are mainly two important aspects that we consider in these CPU scheduling algorithms and
these are following: -
1. Scheduling criteria.
2. Scheduling algorithm.
Scheduling criteria
 Arrival time (A.T): - the time when the process is arrived into ready state is called as
arrival time of the process.
 Burst time (B.T): - the time required by process for its execution is called as burst time of
the process.
 Completion time (C.T): - the time when the process is completed or completes its
execution is called as completed time.
 Turnaround time (T.A.T): - the time difference between completion time and arrival time
is called as turnaround time of process.
T.A.T=C.T-A.T
 Waiting time (W.T): - the time difference T.A.T and B.T.
W.T=T.A.T-B.T
 Response time (R.T): - time difference between first response and arrival time is called as
response time.

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Scheduling algorithm
 First come first serve scheduling (FCFS): - in first come first serve scheduling which job
first enter in the system, that execute first.
 Non-preemptive Shortest job first scheduling (SJF): - in this scheduling algorithm which
job has minimum burst time that job execute first
 Preemptive Shortest job first scheduling (SJF): - in this scheduling all the jobs put in the
ready queue as they arrive. So that we take that job first which have minimum arrive time
with minimum burst time interval.
 Priority based scheduling: - in this scheduling firstly priority assign to each process.
Which process has highest priority that job execute first. If two jobs have same priority
then we apply FCFS (first come first serve) scheduling.
 Round robin scheduling (RR): - in this scheduling fixed time given to each process which
is called time quantum. So that first process is executed in given time quantum, then next
process executed on same manner and so on. Context switching used in preemptive
processes.
 Multilevel queue scheduling: - in this scheduling multiple queues assign to process and
also maintain. Then each queue has its own scheduling algorithm. After that priority
assign to each queue.
 Multilevel feedback scheduling: - this scheduling allows the processes to move between
the queues. So that is uses the many queue and each queue have their own priority.

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Issues
We see many issues while trying to implement these scheduling algorithms. The most
important issue that came up was the problem with covering the input/output time burst
between the executions of process. We also have to handle the input/output devises and the
execution jobs on them.

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References
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Careermonk Publications (29 January 2015).
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Version, Wiley; Eighth edition (20 April 2009).
5. Silberschatz, Galvin and Gagne, Operating System Concepts, Wiley India; 9 edition
(2005).
6. Seymour Lipschutz, Data Structures (SIE), McGraw Hill Education; Revised First edition
(1 February 2014).
7. AHO, Data Structures & Algorithms, Pearson Education India; 1 edition (2002).
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Structure and Algorithmic Puzzles, Careermonk Publications; 2nd edition (16 December
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10. Kurt Mehlhorn and Peter Sanders, Algorithms and Data Structures: The Basic Toolbox,
Springer; 2008 edition (23 June 2008).