Quiz 2 - Memory Management in Operating System

Quiz 2 - Memory Management in Operating System

(Answers are in bold blue)

1. Which of the following types of binding takes place during runtime?

a. Symbolic names to virtual addresses

b. Virtual to physical addresses

c. Both (a) and (b)

2. Suppose the paging hardware with TLB has a 90 percent hit ratio. Page numbers found in the TLB have a total access time of 100 nanoseconds. Those which are not found there have a total access time of 200 nanoseconds. What is the effective access time?

a. 100 nanoseconds

b. 110 nanoseconds

c. 190 nanoseconds

d. 200 nanoseconds

3. If the page table is broken up in to pages, with an outer page-table to select the correct inner table, we are using

a. paged swapping

b. inverted page table

c. multi-level paging

d. none of the above

4. The total space required for an inverted page table is proportional to the number of

a. pages in the virtual memory

b. pages * holes

c. pages + overlays

d. page frames in the physical memory

e. none of the above

5. A system that uses a paging virtual memory system will suffer from

a. external fragmentation

b. internal fragmentation

6. Least Recently Used (LRU) Page Replacement Algorithm bases its decisions to evict a page on

a. future references

b. past references that are organized via a stack structure

c. references that have clean bit

7. Consider a reference string ACDB, where Page A was referenced first, then Page C was referenced in the next cycle, then other actions occurred (e.g., reading, writing, updating bits), then Page D was referenced, and Page B was referenced last. Consider for the given reference string the resulting reference bit (R ) and modified bit (M) for each page as follows: R_A= 0, R_C= 0, R_D= 1, R_B= 1, and the modified bit M_A= 1, M_C= 0, M_D= 1, M_B= 0. Which page out of the given reference string would be the most appropriate to evict?

a. Page A

b. Page C

c. Page D

d. Page B

8. Which page replacement suffers from Belady anomaly?

a. Least Recently Used

b. FIFO

c. Second Chance

9. Once the system detects thrashing, what can the system do to eliminate this problem?

a. Increase the number of CPU-bound jobs

b. Decrease the degree of multiprogramming

c. Install faster CPU

d. None of the above

10. In the paging virtual memory management system, let us consider program B with 10 pages. Each page is 16=2⁴ bytes, and the variable b in program B has the logical address 162. What is the virtual address of b in the representation of (p,d), where p is the page number and d is the page offset?

a. (10,4)

b. (10,2)

c. (16,2)

d. (11,2)

e. invalid address

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*Thanks to Klara Nahrstedt, University of Illinois