operating-system - FIFO 页面替换如何工作？

Question

我正在尝试了解 FIFO 页面替换算法，但我能找到的所有信息都属于以下内容。您能解释一下如何使用引用字符串来评估页面替换算法，使用 FIFO 的特定示例吗？

When a page must be replaced, the oldest page is chosen.

In all our examples, the reference string is

1, 2, 3, 4, 1, 2, 5, 1, 2, 3, 4, 5

3 frame (9 page faults) 4 frame (10 page faults)

Answer 1

页面错误是指内存帧中不存在页面，因此必须向操作系统发送陷阱
并且页面必须添加到框架中。如果没有空间，则需要移除某些东西。
FIFO 是一种确定要删除哪个页面的方法。

这个概念是，首先添加到框架中的任何页面都将首先被删除。这就是 FIFO 的含义。使用你的第一个例子。我将查看引用字符串列表，并向您展示内存的外观。

1:  1      +1 fault
2:  1,2    +1 fault
3:  1,2,3  +1 fault
4:  2,3,4  +1 fault - 1 gets removed because it was the first added
1:  3,4,1  +1 fault - 2 gets removed because it was the first on the list
2:  4,1,2  +1 fault - 3 got removed..
5:  1,2,5  +1 fault - 4 got removed..
1:  1,2,5  No change - 1 is already present so no page fault was required
2:  1,2,5  No change - 2 is already present in the frame
3:  2,5,3  +1 fault - 1 was removed because it is first
4:  5,3,4  +1 fault - Now 2 got removed
5:  5,3,4  No change - No change because 5 is present in one of the frames.

这给出了总共 9 个故障。

您也可以将其视为最旧的页面被删除。

希望我没有犯错:D