If a computer system has a main memory access time of 100ns and a cache access time of 10ns, what is the average memory access time if cache hit rate is 90%?
Q1. If a computer system has a main memory access time of 100ns and a cache access time of 10ns, what is the average memory access time if cache hit rate is 90%?
Answer: 19ns
Explanation: Average memory access time = cache hit rate * cache access time + (1 - cache hit rate) * main memory access time = 0.9 * 10 + 0.1 * 100 = 9 + 10 = 19