GATE CS 2001 Q1.7 — Memory Hierarchy: Cache, Main Memory and Secondary Storage

The correct option is B.

Locality of Reference refers to the tendency of a processor to access the same set of memory locations repeatedly over a short period of time. It has two primary dimensions:

• Spatial Locality: This principle states that if a particular memory location is accessed, nearby memory locations are highly likely to be accessed in the near future (e.g., sequential instruction execution, array traversals). By storing multiple consecutive words in a single cache block, a cache miss on one word brings its neighbors into the cache as well, thereby exploiting spatial locality.
• Temporal Locality: This principle states that if a memory location is accessed, it is likely to be accessed again soon (e.g., loop variables). This is exploited by keeping recently used blocks in the cache.

Note that increasing the block size actually increases the miss penalty because transferring a larger block from main memory to cache takes more time. Thus, option C is incorrect.