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74 lines
2.2 KiB
Python
74 lines
2.2 KiB
Python
"""
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Simple Implementation of the FCFS CPU scheduling algorithm
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FCFS is a non-preemptive CPU scheduling algorithm that
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schedules processes based on their arrival time.
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https://www.geeksforgeeks.org/program-for-fcfs-cpu-scheduling-set-1/
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Author: [Madhav Goyal](https://github.com/mdhvg)
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"""
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def fcfs(processes: list[tuple[int, int, int]]) -> None:
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"""
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Function to implement the FCFS CPU scheduling algorithm
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processes: list of tuples where each tuple contains the
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process_id, arrival_time and burst_time of each process
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>>> processes = [(1, 0, 3), (2, 2, 7), (3, 1, 4), (4, 5, 2)]
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>>> fcfs(processes)
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Average Waiting Time: 6.0
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*---*----*-------*--
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1 3 2 4
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"""
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total_processes = len(processes)
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processes.sort(key=lambda process: process[1])
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waiting_times = [0] * total_processes
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total_waiting_time = 0
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for i in range(1, total_processes):
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waiting_times[i] = processes[i - 1][2] + waiting_times[i - 1]
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total_waiting_time += waiting_times[i]
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print(f"Average Waiting Time: {total_waiting_time / total_processes}")
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"""
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Printing the Gantt Chart for the processes in the FCFS order
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The - and * symbols are used to represent the burst time and
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idle time respectively for each process.
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"""
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last_burst = 0
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for i in range(total_processes):
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print("-" * last_burst, end="")
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print("*", end="")
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last_burst = processes[i][2]
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print("-" * last_burst, end="")
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print("\n", end="")
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last_burst = 0
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for i in range(total_processes):
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print(" " * last_burst, end="")
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print(f"{processes[i][0]}", end="")
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last_burst = processes[i][2]
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print("\n", end="")
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def main() -> None:
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"""
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Main function to demonstrate the FCFS CPU scheduling algorithm
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pass an array of (process_id, arrival_time, burst_time) to fcfs
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>>> processes = [(1, 0, 3), (2, 1, 5), (3, 2, 2), (4, 3, 7), (5, 2, 2)]
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>>> fcfs(processes)
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Average Waiting Time: 6.6
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*---*-----*--*--*-------
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1 2 3 5 4
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"""
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processes = [(1, 0, 3), (2, 1, 5), (3, 2, 2), (4, 3, 7), (5, 2, 2)]
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fcfs(processes)
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if __name__ == "__main__":
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main()
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import doctest
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doctest.testmod()
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