多级缓存访问

To speed up data access , we build cache system. In one system , The L1 cache access time is 5 ns , the L2 cache access time is 50 ns and the memory access time is 400 ns. The L1 cache miss rate is 50% , the L2 cache miss rate is 10%. The average data access time of this system is:(5 Points)
A、5
B、30
C、45
D、50

E、55

解析：

Average Time=Hit_Time+Miss_rate*Miss_penalty

此题目可以解答为：average_time=5+0.5*(50+400*0.1)=50ns

所以应该选D