CPU Scheduling Using Queues

Project Description

This project is a C source code implementation of the Multi-level Feedback Queue scheduling algorithm. The Multilevel feedback queue algorithm categorizes processes into separate queues based on their CPU needs, promotes/demotes processes between queues, gives attention to processes using the CPU quickly, and prioritizes processes with frequent input/output (I/O) operations.

Algorithm Overview:

1. Puts different processes into separate queues based on CPU needs.
2. Promotes/demotes a process to different queues.
3. Gives more attention to processes that use the CPU quickly.
4. Gives priority to processes that perform a lot of input/output (I/O) operations.

Project Implementation:

The multilevel feedback queue algorithm in this project consists of 3 queues:

• First Queue: RoundRobin with quantum = 8 and size = 10
• Second Queue: RoundRobin with quantum = 16 and size = 20
• Third Queue: First Come First Serve (FCFS) with size = 30

There are 100 processes, each assigned a random burst time. The CPU allocates its time as follows:

• First queue: 50%
• Second queue: 30%
• Third queue: 20%

Process Promotion and Demotion:

• Promotion from the first queue to the second queue if not completed in a quantum of 8.
• In the second queue, there is a 50% chance of demotion back to the first queue and a 50% chance of promotion to the third queue if not completed after a quantum of 16.

Challenges Faced

The main challenge in this project was dividing the CPU time appropriately. The time.h library was utilized to aid in the implementation.

How to Run

To run the code, follow these steps:

1. Compile the main.c file.

   gcc main.c -o scheduler

2. Run the executable.

   ./scheduler

The program does not require any user input and should execute smoothly.

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