GATE | GATE CS 2021 | Set 2 | Question 37

Assume a two-level inclusive cache hierarchy, L1 and L2, where L2 is the larger of the two. Consider the following statements.

• S1: Read misses in a write through L1 cache do not result in writebacks of dirty lines to the L2
• S2: Write allocate policy must be used in conjunction with write through caches and no-write allocate policy is used with writeback caches.

Which of the following statements is correct?
(A) S1 is true and S2 is false
(B) S1 is false and S2 is true
(C) S1 is true and S2 is true
(D) S1 is false and S2 is false


Answer: (A)

Explanation:

S1: Write through Cache means simultaneous access for both L1 and L2 and in this case if read miss happen in L1 cache we tried to fetch it from L2 cache and if its dirty then we don’t need to write back to L2 because it’s Write through Cache.

S2: Write allocate policy used for write back cache not for Write through Cache. 

(Correct Option A)

Quiz of this Question