22C:160/55:132 Homework 3 sample solutions
Chen Zhang
Question 1.
(Omitted)Everyone got this question right. Well done!
Question 2.
(a) case memory operation
Read hit 0 read, 0 write
Read miss 2 reads
Write hit 0 read, 1 write
Write miss 2 read, 1 write
So average memory bandwidth used for each memory reference is
75% ·5% ·2 + 25% ·95% ·1 + 25% ·5% ·(2 + 1) = 0.35
Used bandwidth = 0.35·109
109= 35%
(b) case memory operation
any hit 0 read, 0 write
miss and replace clean one 2 reads
miss and replace dirty one 2 reads, 2 writes
So average memory bandwidth used for each memory reference is
5% ·70% ·2 + 5% ·30% ·(2 + 2) = 0.13
Used bandwidth = 0.13·109
109= 13%
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