Question

What is the formula for Hit Ratio?

• A. Miss/(Hit + Miss)
• B. (Hit + Miss)/Miss
• C. (Hit + Miss)/Hit
• D. Hit/(Hit + Miss)

Hint:

- Hit Ratio is used to measure cache efficiency. - Higher Hit Ratios indicate better cache performance, while higher Miss Ratios suggest frequent main memory accesses. - The relation between Hit Ratio and Miss Ratio is: \[ \text{Miss Ratio} = 1 - \text{Hit Ratio} \]

Answer 1

The Correct Option is D

Step 1: Understanding Cache Performance Metrics
- Hit Ratio is the fraction of memory accesses that are found in the cache.
- Miss Ratio is the fraction of memory accesses that are not found in the cache.
- The formula for Hit Ratio is: \[ \text{Hit Ratio} = \frac{\text{Number of Hits}}{\text{Total Accesses}} \] where: \[ \text{Total Accesses} = \text{Hits} + \text{Misses} \]
Step 2: Evaluating the Options
- (A) Incorrect: This is the formula for Miss Ratio, not Hit Ratio.
- (B) Incorrect: This does not represent Hit Ratio; it is an incorrect formulation.
- (C) Incorrect: This is incorrect as it results in an inverse relationship.
- (D) Correct: The correct formula for Hit Ratio is: \[ \frac{\text{Hits}}{\text{Hits} + \text{Misses}} \]