操作系统——进程调度算法 python实现

好的，进程调度算法是操作系统中非常重要的一部分。常见的进程调度算法有先来先服务（FCFS）、短作业优先（SJF）、高响应比优先（HRRN）、时间片轮转（RR）等。下面是这些算法的 Python 实现：

1. 先来先服务（FCFS）：

def FCFS(processes):
    waiting_time = 0
    turn_around_time = 0
    completion_time = 0
    for process in processes:
        completion_time += process['burst_time']
        turn_around_time += completion_time - process['arrival_time']
        waiting_time += turn_around_time - process['burst_time']
    return waiting_time / len(processes), turn_around_time / len(processes)

2. 短作业优先（SJF）：

def SJF(processes):
    processes = sorted(processes, key=lambda x: x['burst_time'])
    waiting_time = 0
    turn_around_time = 0
    completion_time = 0
    for process in processes:
        completion_time += process['burst_time']
        turn_around_time += completion_time - process['arrival_time']
        waiting_time += turn_around_time - process['burst_time']
    return waiting_time / len(processes), turn_around_time / len(processes)

3. 高响应比优先（HRRN）：

def HRRN(processes):
    waiting_time = 0
    turn_around_time = 0
    completion_time = 0
    for i, process in enumerate(processes):
        if i == 0:
            completion_time = process['burst_time']
        else:
            response_ratio_list = []
            for j in range(i):
                response_ratio = (completion_time - processes[j]['arrival_time'] + processes[j]['burst_time']) / processes[j]['burst_time']
                response_ratio_list.append(response_ratio)
            max_response_ratio_index = response_ratio_list.index(max(response_ratio_list))
            selected_process = processes.pop(max_response_ratio_index)
            completion_time += selected_process['burst_time']
            turn_around_time += completion_time - selected_process['arrival_time']
            waiting_time += turn_around_time - selected_process['burst_time']
    return waiting_time / len(processes), turn_around_time / len(processes)

4. 时间片轮转（RR）：

def RR(processes, time_slice):
    waiting_time = 0
    turn_around_time = 0
    completion_time = 0
    while processes:
        for i in range(len(processes)):
            if processes[i]['burst_time'] > time_slice:
                completion_time += time_slice
                processes[i]['burst_time'] -= time_slice
            else:
                completion_time += processes[i]['burst_time']
                turn_around_time += completion_time - processes[i]['arrival_time']
                waiting_time += turn_around_time - processes[i]['burst_time']
                processes.pop(i)
                break
    return waiting_time / len(processes), turn_around_time / len(processes)

这里的 `processes` 是一个列表，其中每个元素是一个字典，表示一个进程的信息，如下所示：

processes = [
    {'name': 'P1', 'arrival_time': 0, 'burst_time': 8},
    {'name': 'P2', 'arrival_time': 1, 'burst_time': 4},
    {'name': 'P3', 'arrival_time': 2, 'burst_time': 9},
    ...
]

在这个列表中，每个进程有一个名称、到达时间和执行时间。你可以根据自己的需要修改这些信息，来测试这些进程调度算法的实现。