NIMCET 2008 — Computer PYQ
NIMCET | Computer | 2008The main disadvantage of direct mapping of cache organization is that
Choose the correct answer:
- A.
it doesn’t allow simultaneous access to the intended data and its tag
- B.
it is more expensive than other type of organizations.
- C.
the cache hit ratio is degreaded if two or more blocks used alternatively map onto the same block frame in the cache.
(Correct Answer) - D.
the number of blocks required for the cache increases linearly with the size of the main memory.
the cache hit ratio is degreaded if two or more blocks used alternatively map onto the same block frame in the cache.
Explanation
Explanation:
In Direct Mapping, every block of main memory has exactly one specific line in the cache where it can be stored. This relationship is defined by the formula:
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The Problem (Thrashing): Because multiple main memory blocks map to the same single cache line, a conflict occurs if a program needs to access two different blocks that happen to map to the same spot.
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If the program alternates between these two blocks, the CPU will constantly kick one out to bring the other in. This leads to a massive drop in the hit ratio, even if the rest of the cache is completely empty.