页表条目的大小是多少? [英] What is page table entry size?

问题描述

我找到了这个例子.

请考虑具有32位逻辑地址空间的系统.如果页面 在这样的系统中，文件大小为4 KB(2 ^ 12)，则页表可能包含 最多一百万个条目(2 ^ 32/2 ^ 12).假如说 每个条目由4个字节组成，每个进程可能仅针对页表就需要多达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.

每个条目包含4个字节是什么意思?为什么每个进程可能需要多达4 MB的页表物理地址?

What is the meaning of each entry consists of 4 bytes and why each process may need up to 4 MB of physical address space for the page table?

推荐答案

页表是操作系统从虚地址到物理地址的转换表，操作系统使用这些地址来人为地增加系统中可用的主内存总量.

A page table is a table of conversions from virtual to physical addresses that the OS uses to artificially increase the total amount of main memory available in a system.

物理内存是位于内存(DRAM)地址中的实际位，而虚拟内存是OS通过告诉它们所在的位置来依赖"进程的位置，以便执行诸如允许2 ^ 64位的操作.地址空间，尽管事实上2 ^ 34位是通常使用的最大RAM. (2 ^ 32位为4 GB，因此2 ^ 34为16 gb.) 每个进程的大多数默认页面表大小为4096 kb，但是如果该进程需要更多进程空间，则页面表条目的数量会增加.页面表的大小最初也可以分配为更大或更小或更大的内存，通常对于大多数进程来说，最好只有4 kb.

Physical memory is the actual bits located at addresses in memory (DRAM), while virtual memory is where the OS "lies" to processes by telling them where it's at, in order to do things like allow for 2^64 bits of address space, despite the fact that 2^34 bits is the most RAM normally used. (2^32 bits is 4 gigabytes, so 2^34 is 16 gb.) Most default page table sizes are 4096 kb for each process, but the number of page table entries can increase if the process needs more process space. Page table sizes can also initially be allocated smaller or larger amounts or memory, it's just that 4 kb is usually the best size for most processes.

请注意，页面表是页面条目的表.两者的大小可以不同，但​​是页面表的大小通常为4096 kb或4 mb，并且通过添加更多条目来增加页面表的大小.

Note that a page table is a table of page entries. Both can have different sizes, but page table sizes are most commonly 4096 kb or 4 mb and page table size is increased by adding more entries.

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