考虑下述页面走向: 1,2,5,6,2,1,3,4,2,1,5,3,7,6,3,2,1,2,3,6 当内存块数量分别为3,5时,试问FIFO(先进先出)和LRU(最近最少使用)置换算法的缺页次数各是多少? (注意,所有内存块最初都是空的,凡第一次用到的页面都产生一次缺页。)
时间: 2024-03-31 15:33:24 浏览: 21
假设内存块数量为3时,使用FIFO和LRU置换算法的缺页次数分别为:
FIFO:缺页次数为11次。
| 1 | 2 | 5 | 1 | 2 | 5 | 3 | 4 | 2 | 1 | 5 | 3 | 7 | 6 | 3 | 2 | 1 | 2 | 3 | 6 |
| - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - |
| 1 | 2 | 5 | 1 | 2 | 5 | 3 | 4 | 2 | 1 | 5 | 3 | 7 | 6 | 3 | 2 | 1 | 2 | 3 | 6 |
| | 1 | 2 | 2 | 5 | 5 | 3 | 4 | 4 | 1 | 1 | 1 | 7 | 7 | 6 | 6 | 2 | 2 | 3 | 3 |
| | | 5 | 5 | 3 | 3 | 4 | 4 | 1 | 1 | 1 | 1 | 1 | 6 | 6 | 2 | 2 | 3 | 3 | 6 |
LRU:缺页次数为9次。
| 1 | 2 | 5 | 1 | 2 | 5 | 3 | 4 | 2 | 1 | 5 | 3 | 7 | 6 | 3 | 2 | 1 | 2 | 3 | 6 |
| - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - |
| 1 | 2 | 5 | 1 | 2 | 5 | 3 | 4 | 4 | 1 | 1 | 1 | 7 | 6 | 6 | 2 | 2 | 2 | 3 | 3 |
| | 1 | 2 | 2 | 5 | 5 | 5 | 4 | 4 | 4 | 4 | 1 | 1 | 1 | 6 | 6 | 6 | 2 | 2 | 3 |
| | | 3 | 3 | 3 | 3 | 5 | 5 | 5 | 5 | 5 | 5 | 7 | 7 | 7 | 7 | 7 | 7 | 7 | 6 |
假设内存块数量为5时,使用FIFO和LRU置换算法的缺页次数分别为:
FIFO:缺页次数为10次。
| 1 | 2 | 5 | 6 | 2 | 1 | 3 | 4 | 2 | 1 | 5 | 3 | 7 | 6 | 3 | 2 | 1 | 2 | 3 | 6 |
| - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - |
| 1 | 2 | 5 | 6 | 2 | 1 | 3 | 4 | 4 | 1 | 1 | 1 | 7 | 7 | 6 | 6 | 2 | 2 | 3 | 3 |
| | 1 | 2 | 2 | 5 | 5 | 5 | 4 | 4 | 4 | 4 | 1 | 1 | 1 | 6 | 6 | 6 | 6 | 3 | 3 |
| | | 3 | 6 | 6 | 6 | 6 | 6 | 1 | 1 | 1 | 1 | 7 | 7 | 7 | 2 | 2 | 2 | 2 | 2 |
LRU:缺页次数为8次。
| 1 | 2 | 5 | 6 | 2 | 1 | 3 | 4 | 2 | 1 | 5 | 3 | 7 | 6 | 3 | 2 | 1 | 2 | 3 | 6 |
| - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - |
| 1 | 2 | 5 | 6 | 2 | 1 | 3 | 4 | 4 | 4 | 4 | 4 | 7 | 7 | 6 | 6 | 6 | 6 | 3 | 3 |
| | 1 | 2 | 2 | 5 | 5 | 5 | 4 | 4 | 1 | 1 | 1 | 1 | 1 | 6 | 6 | 6 | 6 | 6 | 6 |
| | | 3 | 3 | 6 | 6 | 6 | 6 | 2 | 2 | 5 | 5 | 7 | 7 | 7 | 7 | 7 | 2 | 2 | 3 |
其中,- 表示该内存块为空。
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