第 20 章 分页：较小的表

Homework

This fun little homework tests if you understand how a multi-level page table works. And yes, there is some debate over the use of the term “fun” in the previous sentence. The program is called, perhaps unsurprisingly: paging-multilevel-translate.py; see the README for details.

Questions

1. With a linear page table, you need a single register to locate the page table, assuming that hardware does the lookup upon a TLB miss. How many registers do you need to locate a two-level page table? A three-level table?

不管时几级页表，只需要一个寄存器即可，该寄存器存储最顶层页表的物理地址

2. Use the simulator to perform translations given random seeds 0, 1, and 2, and check your answers using the -c flag. How many memory references are needed to perform each lookup?

二级页表需要两次访存

python paging-multilevel-translate.py -s 1 -c

3. Given your understanding of how cache memory works, how do you think memory references to the page table will behave in the cache? Will they lead to lots of cache hits (and thus fast accesses?) Or lots of misses (and thus slow accesses)?