GATE-2024-CS1(Forenoon)
March 23, 2025GATE 2022
March 24, 2025GATE-2024-CS1(Forenoon)
| Question 53 |
| A read miss in WBC never evicts a dirty block
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| A read miss in WTC never triggers a write back operation of a cache block to main memory | |
| A write hit in WBC can modify the value of the dirty bit of a cache block | |
| A write miss in WTC always writes the victim cache block to main memory before loading the missed block to the cache | |
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In a Write Through Cache (WTC), every write operation to the cache is immediately propagated to main memory. However, a read miss only involves reading data from main memory into the cache; it does not trigger any write back operations. Therefore, a read miss in WTC does not cause any write back operation. This statement is true.
(C) A write hit in WBC can modify the value of the dirty bit of a cache block
In a Write Back Cache (WBC), a write hit means that the data to be written is already present in the cache. When a write occurs, the value of the dirty bit for the block is set to indicate that the block has been modified. Thus, a write hit in WBC will modify (set) the dirty bit of the cache block. This statement is true.
In a Write Through Cache (WTC), every write operation to the cache is immediately propagated to main memory. However, a read miss only involves reading data from main memory into the cache; it does not trigger any write back operations. Therefore, a read miss in WTC does not cause any write back operation. This statement is true.
(C) A write hit in WBC can modify the value of the dirty bit of a cache block
In a Write Back Cache (WBC), a write hit means that the data to be written is already present in the cache. When a write occurs, the value of the dirty bit for the block is set to indicate that the block has been modified. Thus, a write hit in WBC will modify (set) the dirty bit of the cache block. This statement is true.