Question 14291 – Computer-Organization
December 25, 2023Question 10626 – GATE 2008-IT
December 25, 2023Cache
| Question 12 |
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 write back caches.
| S1is true and S2is false | |
| S1is false and S2is false | |
| S1is true and S2is true | |
| S1is false and S2is true |
S1: In a write through cache the writing happens to both the L1 and L2 caches simultaneously. It is also given as the inclusive hierarchy. Here L1 is a subset of L2. So when there is a cache read miss in L1 we try to fetch the content from L2. If the block containing that missed word is dirty in the L1 cache, since it is a write through cache the same content would have also been written to the L2 cache also earlier itself. So there is no need to write back the dirty lines again to the L2 cache on a cache miss. Hence S1 is true.
S2: Generally no-write allocate is used with write through cache and write allocate is used with write back cache. Hence S2 is false.
S1: In a write through cache the writing happens to both the L1 and L2 caches simultaneously. It is also given as the inclusive hierarchy. Here L1 is a subset of L2. So when there is a cache read miss in L1 we try to fetch the content from L2. If the block containing that missed word is dirty in the L1 cache, since it is a write through cache the same content would have also been written to the L2 cache also earlier itself. So there is no need to write back the dirty lines again to the L2 cache on a cache miss. Hence S1 is true.
S2: Generally no-write allocate is used with write through cache and write allocate is used with write back cache. Hence S2 is false.