PDF《操作系统原理与设计》

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0102 0105 陈香兰 操作系统原理与设计 Page Replacement Allocation of Frames 小结和作业 Basic Page Replacement First-In-First-Out (FIFO) Algorithm Optimal Algorithm Least Recently Used (LRU) Algorithm LRU Approximation Algorithms Counting Algorithms Page-Bu?eing Algorithms . . Page Replacement Algorithms II Assuming page size =

100 B, then its corresponding page reference string is:

1 4

1 6

1 6

1 6

1 6

1 how many page faults? determined by the number of page frames assigned to the process if ≥ 3, then only

3 page faults if = 1,

11 pages faults 陈香兰 操作系统原理与设计 Page Replacement Allocation of Frames 小结和作业 Basic Page Replacement First-In-First-Out (FIFO) Algorithm Optimal Algorithm Least Recently Used (LRU) Algorithm LRU Approximation Algorithms Counting Algorithms Page-Bu?eing Algorithms . . Graph of Page Faults Versus The Number of Frames 陈香兰 操作系统原理与设计 Page Replacement Allocation of Frames 小结和作业 Basic Page Replacement First-In-First-Out (FIFO) Algorithm Optimal Algorithm Least Recently Used (LRU) Algorithm LRU Approximation Algorithms Counting Algorithms Page-Bu?eing Algorithms In all our examples, the reference string is 1, 2, 3, 4, 1, 2, 5, 1, 2, 3, 4,

5 another one is 7,0,1,2,0,3,0,4,2,3,0,3,2,1,2,0,1,7,0,1 陈香兰 操作系统原理与设计 Page Replacement Allocation of Frames 小结和作业 Basic Page Replacement First-In-First-Out (FIFO) Algorithm Optimal Algorithm Least Recently Used (LRU) Algorithm LRU Approximation Algorithms Counting Algorithms Page-Bu?eing Algorithms . . Outline . ..

1 Page Replacement Basic Page Replacement First-In-First-Out (FIFO) Algorithm Optimal Algorithm Least Recently Used (LRU) Algorithm LRU Approximation Algorithms Counting Algorithms Page-Bu?eing Algorithms . ..

2 Allocation of Frames . ..

3 小结和作业 陈香兰 操作系统原理与设计 Page Replacement Allocation of Frames 小结和作业 Basic Page Replacement First-In-First-Out (FIFO) Algorithm Optimal Algorithm Least Recently Used (LRU) Algorithm LRU Approximation Algorithms Counting Algorithms Page-Bu?eing Algorithms . . First-In-First-Out (FIFO) Algorithm I . ..

1 example

1 . ..

2 Reference string: 1, 2, 3, 4, 1, 2, 5, 1, 2, 3, 4,

5 if

3 frames 陈香兰 操作系统原理与设计 Page Replacement Allocation of Frames 小结和作业 Basic Page Replacement First-In-First-Out (FIFO) Algorithm Optimal Algorithm Least Recently Used (LRU) Algorithm LRU Approximation Algorithms Counting Algorithms Page-Bu?eing Algorithms . . First-In-First-Out (FIFO) Algorithm II if

4 frames Belady'

s (贝莱迪) Anomaly: more frames ? more page faults 陈香兰 操作系统原理与设计 Page Replacement Allocation of Frames 小结和作业 Basic Page Replacement First-In-First-Out (FIFO) Algorithm Optimal Algorithm Least Recently Used (LRU) Algorithm LRU Approximation Algorithms Counting Algorithms Page-Bu?eing Algorithms . . FIFO Illustrating Belady'

s Anomaly more memory, better performance? MAY BE NOT!! Belady'

s anomaly 陈香兰 操作系统原理与设计 Page Replacement Allocation of Frames 小结和作业 Basic Page Replacement First-In-First-Out (FIFO) Algorithm Optimal Algorithm Least Recently Used (LRU) Algorithm LRU Approximation Algorithms Counting Algorithms Page-Bu?eing Algorithms . . Outline . ..

1 Page Replacement Basic Page Replacement First-In-First-Out (FIFO) Algorithm Optimal Algorith........