Question

Consider a system which uses cache. The uncached access time is 6 times faster than access to cache. Cache hit ratio is 80%. The ratio of cached memory access time to uncached memory access time is______.

• A. 0.72
• B. 0.22
• C. 0.33
• D. 0.65

Answer 1

The correct option is C 0.33

Cache access time = x

Main memory (uncache) access time = 6x

H = 80% or 0.8

$Ratio=\frac{0.8\times x+0.2\times 6x}{6x}$

$=\frac{2x}{6x}$

$=\frac{1}{3}=0.33$