计算页表的大小

时间:2015-04-21 04:07:06

标签: page-tables

我的作业有以下提示:

The page size for a virtual memory system is 8KB.
The instruction TLB is direct-mapped with 2 sets and each block contains one translation.
^(I don't believe this is relevant for the following 3 questions, as there are two more questions about the TLB)

The number of bits in a virtual address is 20.
The number of bits in a physical address is 15.

(1) What is the number of virtual pages?

我想我已经找到了这个。

页面尺寸= 8 * 2^10 = 8192,因此偏移量为13 bits 虚拟页码= 20 - 13 = 7
虚拟页面= 2^7页面

(2) What is the number of physical pages?

在这里,我有点困惑。我想我应该将有效,脏和引用位添加到物理页码(2,来自15 - 13)。但是5 * 2^7 = 640 bytes,似乎非常小。

(3) How many bits are used in the virtual address for the page offset?

上面回答,它似乎是13 bits

有人能指出我正确的方向吗?谢谢!

1 个答案:

答案 0 :(得分:1)

有效,脏和引用位在页表条目中,但不是地址位的一部分。因此,使用您的结果有2^24个物理页面。

是的,这似乎很小,但意识到物理内存只有2^1532K个字节。