操作系统模拟之请求分页算法。
文件共1份，代码如下：

import math
import os
import random
import copydef alo_opt():print("您选择了OPT算法，执行结果如下：")print("访问页面  物理块  缺页中断")temp_queue = []sum_changed = 0for i in range(page_size):flag_changed = Falseif len(temp_queue) < temp_queue_size and temp_queue.count(page_queue[i]) == 0:temp_queue.append(page_queue[i])elif temp_queue.count(page_queue[i]) == 0:appear_position = []for j in range(temp_queue_size):appear_position.append(page_size)for j in range(i + 1, page_size):if temp_queue.count(page_queue[j]) > 0 and appear_position[temp_queue.index(page_queue[j])] == page_size:appear_position[temp_queue.index(page_queue[j])] = jremotest_position = appear_position.index(max(appear_position))temp_queue[remotest_position] = page_queue[i]sum_changed = sum_changed + 1flag_changed = Trueoutput_queue = copy.deepcopy(temp_queue)for j in range(temp_queue_size - len(temp_queue)):output_queue.append("&")print('{}  {}  {}'.format(page_queue[i], output_queue, flag_changed))print()print('页面访问序列总长{0}，OPT算法共发生缺页中断{1}次，缺页率为{1}/{0}'.format(page_size, sum_changed))def alo_fifo():print("您选择的是先进先出页面置换算法")print("访问页面  物理块  缺页中断")temp_queue = []sum_changed = 0appear_time = []for i in range(page_size+1):appear_time.append(page_size)for i in range(page_size):flag_changed = Falseif len(temp_queue) < temp_queue_size and temp_queue.count(page_queue[i]) == 0:temp_queue.append(page_queue[i])appear_time[page_queue[i]] = ielif temp_queue.count(page_queue[i]) == 0:target_index = 0min_time = page_sizefor j in range(0, temp_queue_size):if appear_time[temp_queue[j]] < min_time:min_time = appear_time[temp_queue[j]]target_index = jappear_time[temp_queue[target_index]] = page_sizetemp_queue[target_index] = page_queue[i]appear_time[page_queue[i]] = isum_changed = sum_changed + 1flag_changed = Trueoutput_queue = copy.deepcopy(temp_queue)for j in range(temp_queue_size - len(temp_queue)):output_queue.append("&")print('{}  {}  {}'.format(page_queue[i], output_queue, flag_changed))print()print('页面访问序列总长{0}，FIFO算法共发生缺页中断{1}次，缺页率为{1}/{0}'.format(page_size, sum_changed))def alo_lru():print("您选择的是最近最久未使用页面置换算法")print("访问页面  物理块  缺页中断")temp_queue = []sum_changed = 0recent_used = []for i in range(page_size+1):recent_used.append(0)for i in range(page_size):flag_changed = Falseif len(temp_queue) < temp_queue_size and temp_queue.count(page_queue[i]) == 0:temp_queue.append(page_queue[i])elif temp_queue.count(page_queue[i]) == 0:target_index = 0min_time = page_sizefor j in range(0, temp_queue_size):if recent_used[temp_queue[j]] < min_time:min_time = recent_used[temp_queue[j]]target_index = jtemp_queue[target_index] = page_queue[i]recent_used[page_queue[i]] = isum_changed = sum_changed + 1flag_changed = Trueelse:recent_used[page_queue[i]] = ioutput_queue = copy.deepcopy(temp_queue)for j in range(temp_queue_size - len(temp_queue)):output_queue.append("&")print('{}  {}  {}'.format(page_queue[i], output_queue, flag_changed))print()print('最近最久未使用页面置换算法缺页{0}次, 缺页率为{0}/{1}'.format(sum_changed, page_size))def alo_clock():print("您选择的是时钟页面置换算法")print("访问页面  物理块  缺页中断")temp_queue = []sum_changed = 0flag = {}for i in range(0, page_size+1):flag[i] = Falsepoint = 0for i in range(page_size):flag_changed = Falseif len(temp_queue) < temp_queue_size and temp_queue.count(page_queue[i]) == 0:temp_queue.append(page_queue[i])flag[page_queue[i]] = Truepoint = temp_queue.index(page_queue[i]) + 1elif temp_queue.count(page_queue[i]) == 1:point = temp_queue.index(page_queue[i])flag[page_queue[i]] = Trueelif temp_queue.count(page_queue[i]) == 0:while True:if not flag[temp_queue[point % temp_queue_size]]:temp_queue[point % temp_queue_size] = page_queue[i]point = point + 1sum_changed = sum_changed + 1flag_changed = Truebreakelse:flag[temp_queue[point % temp_queue_size]] = Falsepoint = point + 1output_queue = copy.deepcopy(temp_queue)for j in range(len(temp_queue)):if flag[temp_queue[j]]:output_queue[j] = str(temp_queue[j]) + "*"for j in range(temp_queue_size - len(temp_queue)):output_queue.append("&")print('{}  {}  {}'.format(page_queue[i], output_queue, flag_changed))print()print('时钟页面置换算法缺页{0}次, 缺页率为{0}/{1}'.format(sum_changed, page_size))print("欢迎进入操作系统课程演示系统之页面置换算法！")
print()flag_exit = False
while True:if flag_exit == True:print("您已成功退出系统！")breakprint("请输入页面访问序列长度（15-25，含端点）：")while True:page_size = int(input())if page_size >= 15 and page_size <= 25:breakprint("您输入的页面访问序列长度超出给定范围，请重新输入15-25（含端点）的数字：")print("请输入物理块个数（3-5，含端点）：")while True:temp_queue_size = int(input())if temp_queue_size >= 3 and temp_queue_size <= 5:breakprint("您输入的物理块个数超出给定范围，请重新输入3-5（含端点）的数字：")print()page_queue = []print("选择用户输入请输入1")print("选择随机生成请输入2")data_produce_choice = int(input())if data_produce_choice == 2:for i in range(page_size):page_queue.append(random.randint(0, 5))else:while True:print('请输入0-5数字组成的无规律字符串作为页面访问序列，长度为{}'.format(page_size))flag_digit = Truetemp = input().split(" ")key = ["0", "1", "2", "3", "4", "5"]for i in temp:if key.count(i) == 0:flag_digit = Falseif not flag_digit:print("您输入的序列有误，请重新输入")elif len(temp) < page_size:print('您已输入{}长度的字符串，还需输入{}长度的字符串'.format(len(temp), page_size - len(temp)))print('请继续输入0-5数字组成的无规律字符串作为页面访问序列，长度为{}'.format(page_size - len(temp)))temp_plus = input().split(" ")if len(temp_plus) != page_size - len(temp):print("您再次输入错误，序列需要全部重新输入")continuefor i in temp:page_queue.append(int(i))for i in temp_plus:page_queue.append(int(i))elif len(temp) > page_size:print("您输入的字符串超长，系统将进行自动截取Y或由用户重新输入N（Y/N）")if input() == "Y":for i in range(page_size):page_queue.append(int(temp[i]))breakelse:continueelse:for i in temp:page_queue.append(int(i))breakprint()print('页面访问序列为：{}'.format(page_queue))print('物理块个数为：{}'.format(temp_queue_size))print()while True:print("选择最佳置换算法请输入1")print("选择先进先出页面置换算法请输入2")print("选择最近最久未使用页面置换算法请输入3")print("选择时钟页面置换算法请输入4")menu_choice = int(input())if menu_choice == 1:alo_opt()elif menu_choice == 2:alo_fifo()elif menu_choice == 3:alo_lru()elif menu_choice == 4:alo_clock()else:print("您的算法选择错误，请重新输入！")print()print("继续尝试其他算法请输入1")print("更换数据请输入2")print("退出程序请输入3")end_choice = int(input())if end_choice == 2:breakelif end_choice == 3:flag_exit = True