Homework 13
注：虽然题目是英文的，但是大家写答案的时候可以使用中文。
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Problem1
Problem 1
In this exercise, we will examine space/time optimizations for page tables. The following table
shows parameters of a virtual memory system.
1) For a single level page table, how many page table entries(PTEs) are needed? How much
physical memory is needed for storing the page table?
2) Using a multilevel page table can reduce the physical memory consumption of page tables, by
only keeping active PTEs in physical memory. How many levels of page tables will be needed
in this case? And how many memory references are needed for address translation if missing in
TLB?
3) An inverted page table can be used to further optimize space and time. How many PTEs are
needed to store the page table? Assuming a hash table implementation, what are the common
case and worst case numbers of memory references needed for servicing a TLB miss?
The following table shows the contents of a 4entry TLB. Entry
4) Under what scenarios would entry 2’s valid bit be set to zero?
5) What happens when an instruction writes to VA page 30? When would a software managed
TLB be faster than a hardware managed TLB?
6) What happens when an instruction writes to VA page xxx?
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