Operating Systems
Assignment 01: Scheduling
COMP2012J
2025-26
1 Scheduling Simulator
Please download the scheduling simulator skeleton code from the moodle. The scheduling simulator illustrates
the behaviour of scheduling algorithms against a simulated mix of process loads. The user can specify the number
of processes, the mean and standard deviation for compute time and I/O blocking time for each process, and
the duration of the simulation. At the end of the simulation, a statistical summary is presented.
We have given the implementation of FIFO scheduling as an example of how to implement a scheduling algorithm
in the given environment. You are allowed to use any development environment you prefer. Please go through
the instructions carefully and complete the assignment.
2 Running the Simulator
• Compile the java code using the following command.
1 $ javac *. java
• The program reads a configuration file (scheduling.conf) and writes two output files (Summary-Results
and Summary-Processes).
• To run the program, enter the following in the command line.
1 $ java Scheduling scheduling . conf
• The program will display “Working...” while the simulation is working, and “Completed.” when the
simulation is complete.
• The simulator reads parameters from the configuration file (“scheduling.conf”).
2.1 The configuration file
• The configuration file (scheduling.conf) is used to specify various parameters for the simulation.
• There are a number of options which can be specified in the configuration file. These are summarized in
the table below.
Keyword Values Description
numprocess n The number of processes to create for the simulation.
meandev n The average length of time in milliseconds that a process should execute before terminating.
standdev n
The number of standard deviations from the average length of time a process should
execute before terminating.
process n
The amount of time in milliseconds that the process should execute before blocking for input
or output. There should be a separate process directive for each process specified by the
numprocess directive.
runtime n The maximum amount of time the simulation should run in milliseconds.
timeslice n The amount of time for a timeslice in the round-robin implementation.
test 1 or 0 If testing == 1, system use meandev as each process’s length. This is for testing purposes.
3 FIFO Scheduling
• Open the ‘SchedulingAlgorithm.java’ file. You can find the implementation of the FIFO scheduling algo rithm here.
• Please go through the FIFO method carefully and try to understand how this version of FIFO algorithm
works. Specifically, give attention to the timer-counter usage in the implementation.
University College Dublin 1
Operating Systems
Assignment 01: Scheduling
COMP2012J
2025-26
• Try to identify the design decisions taken when implementing this algorithm. I.e: assumptions, scope and
limitations.
• Change values in the configuration file and try different types of workloads. Set ‘test’ to ‘0’ when you are
experimenting.
4 Round-robin Scheduling
• Implement the round-robin scheduling algorithm in the ‘SchedulingAlgorithm.java’ file. Use the given
‘.test’ output files as references.
• Assume that the time each process stays in the blocked state is 0.
• Use the print functions in the ‘SchedulingAlgorithm.java’ file to update the ‘Summary-Processes’ file.
5 Testing
• After implementation, execute the ‘run test.py’ to check the accuracy of your algorithm. Please note that
this script is given for your convenience. It is not mandatory to use this. It is written in python and
requires a working installation of python3 to run.
• It compares your output file with a preprocessed output file, which is generated with a round-robin
scheduling algorithm.
• You can add more of your own tests if you prefer. Please add those new tests to ‘tests.txt’ file.
6 Submission
• Submit the ‘SchedulingAlgorithm.java’ file to the submission link in the moodle before the deadline.
• You will be marked against a set of test cases.
• Please keep the code clean and add comments. There will be marks for the code quality and comments.
7 Assessment
Your submission will be tested against input that we have designed. To help you get started, a file called
run test.py has been supplied. Keep the following points in mind:
• run test.py is only a sample. The actual test will contain more tests.
• Do NOT change the input/output format of the code given to you. Any change will result in your code
failing the tests.
• Do NOT output anything other than what has been asked for. If you have added any outputs for your
own convenience, you should remove/comment them before submission.
University College Dublin 2

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