If cache access time is 100ns, main memory access time is 1000ns and the hit raio is 0.9. Find the average access time and also define hit ratio.

If cache access time is 100ns, main memory access time is 1000ns and the hit raio is 0.9. Find the average access time and also define hit ratio.

RGPV 2020
Solution:
Given,
Cache access time = 100ns
Memory access time = 1000ns
Hit ratio = 0.9
Average access time = Hit ratio x Cache access time + (1 – Hit ratio) x Main memory access time
Using above formula:
Average access time = 0.9 x 100ns + (1 – 0.9) x 1000ns = 190ns