Answer:
Hit rate = 80%
Miss rate = 20%
Hit time = 0.3 ns
Miss penalty = 0.4 ns
AMAT ≈ 3.875 ns
Step-by-step explanation:
8 out of 10 = 0.3ns. to return data ( also finds data in the upper level )
2 out of 10 = 0.7 ns to return data
a) Hit rate in upper level memory
= 8/10 * 100 = 80%
b) Miss rate
= 2/ 10 * 100 = 20%
c) Hit time in the upper level memory
Hit time = 0.3 ns
d) Miss penalty
This is the time taken by the missed requests to return their own data
= 0.7 ns - 0.3 ns = 0.4 ns
e) AMAT ( average memory access time )
Hit rate = 80% , Hit time = 0.3ns
miss rate = 20% Miss time = 0.7 ns
hence AMAT = (0.3 / 0.8 ) + (0.7 / 0.2 )
≈ 3.875 ns