A CPU has a cache with a hit ratio of 0.9. If the cache access time is 1 ns, what is the average memory access time?
Q1. A CPU has a cache with a hit ratio of 0.9. If the cache access time is 1 ns, what is the average memory access time?
Answer: 1.1 ns
Explanation: Assuming a miss penalty of 10 ns, average access time = (0.9 * 1) + (0.1 * 11) = 0.9 + 1.1 = 2 ns, but if miss penalty is 1 ns (1 + 1*(1-0.9)) = 1.1 ns