Question

If a cache access requires one clock cycle and dealing with cache misses requires an additional five clock cycles, which of the following cache hit rates results in an effective access time of 2 clock cycles?a) 70%.
b) 80%.
c) 85%.
d) 90%.

Answer 1

Answer:

B. 80%

Explanation:

To assertain:

1 hit takes 1 clock cycle while 1 miss takes 6 clock cycles

Assuming that:

1. we have 100 accesses in total,
2. p are hits,
3. 100 - p are misses

$So, p + (100 - p)*6 = 200\\ \\p+600-6p = 200\\\\-5p + 600 = 200\\\\5p = 600 -200\\\\p = \frac{400}{5} \\\\p= 80$

Hence, option B. 80% will result in an effective access time of 2 clock cycles.