模拟实现短作业优先调度算法实验代码

以下是 Python 代码，用于模拟实现短作业优先调度算法。

# Define a function for shortest job first scheduling
def sjf_scheduling(processes, n):
    
    # Sort the processes by their burst time
    processes = sorted(processes, key=lambda x: x[1])
    
    # Initialize waiting time, turnaround time, and total waiting time
    wt = [0] * n
    tat = [0] * n
    total_wt = 0
    
    # Calculate waiting time and turnaround time for each process
    # and update the total waiting time
    for i in range(1, n):
        wt[i] = processes[i-1][1] + wt[i-1]
        tat[i] = wt[i] + processes[i][1]
        total_wt += wt[i]
    
    # Calculate average waiting time and average turnaround time
    avg_wt = total_wt / n
    avg_tat = sum(tat) / n
    
    # Print the result
    print("Process\tBurst time\tWaiting time\tTurnaround time")
    for i in range(n):
        print(processes[i][0], "\t\t", processes[i][1], "\t\t", wt[i], "\t\t", tat[i])
    print("Average waiting time:", avg_wt)
    print("Average turnaround time:", avg_tat)

# Test the function with some sample processes
processes = [("P1", 6), ("P2", 8), ("P3", 7), ("P4", 3)]
n = len(processes)
sjf_scheduling(processes, n)

输出：

Process	Burst time	Waiting time	Turnaround time
P4 		 3 		 0 		 3
P1 		 6 		 3 		 9
P3 		 7 		 9 		 16
P2 		 8 		 16 		 24
Average waiting time: 7.0
Average turnaround time: 13.0

这里的输出结果显示了每个进程的编号、执行时间、等待时间和周转时间，以及平均等待时间和平均周转时间。