正在读原代码的书,关于内存管理有些不明白,请教大家

z3518

正在读&lt;<Understanding the Linux Kernel>&gt;,在第二章中,讲到页表的时候,说到了两层的好处,原文如下.

If a simple one-level Page Table was used, then it would require up to 220 entries (i.e., at 4 bytes per entry, 4 MB of RAM) to represent the Page Table for each process (if the process used a full 4 GB linear address space), even though a process does not use all addresses in that range.

不明白为什么如果用一层的方式,4G的虚拟内存会是220 个entries,是怎么算的啊?望指教,多谢!

jjww

不是220,是2^20

z3518

哇,不会吧,真的是2^20??原来电子版上写错了??我说怎么搞不明白呢,
多谢了!!