计算页表大小 [英] Calculating Page Table Size

问题描述

我正在阅读页表的示例，并且发现了这一点:

I'm reading through an example of page tables and just found this:

请考虑具有32位逻辑地址空间的系统.如果在这样的系统中页面大小为4 KB(2 ^ 12)，则页面表最多可以包含一百万个条目(2 ^ 32/2 ^ 12).假设每个条目包含4个字节，则每个进程可能仅对于页表就需要多达4 MB的物理地址空间.

Consider a system with a 32-bit logical address space. If the page size in such a system is 4 KB (2^12), then a page table may consist of up to 1 million entries (2^32/2^12). Assuming that each entry consists of 4 bytes, each process may need up to 4 MB of physical address space for the page table alone.

我不太了解这4MB的结果.它代表实际的页表占用的空间吗?

I don't really understand what this 4MB result represents. Does it represent the space the actual page table takes up?

推荐答案

由于我们的虚拟地址空间为 2 ^ 32 ，并且每个页面的大小为 2 ^ 12 ，我们可以存储(2 ^ 32/2 ^ 12)= 2 ^ 20页.由于此页表中的每个条目的地址大小均为4个字节，因此我们有 2 ^ 20 * 4 = 4MB .因此，页表占用4MB内存.

Since we have a virtual address space of 2^32 and each page size is 2^12, we can store (2^32/2^12) = 2^20 pages. Since each entry into this page table has an address of size 4 bytes, then we have 2^20*4 = 4MB. So the page table takes up 4MB in memory.

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