1. CS2100 Computer Organization
Cache Exercises

2. Direct Mapped Cache
We have a 64 byte direct-mapped cache with 4 word blocks.
Questions:
Sketch layout for 32-bit address.
Calculate TOTAL amount of SRAM needed to implement this cache, assuming write- back policy.
Calculate the hit rate for the following memory (byte) addresses:
0, 32, 33, 64, 8, 80, 18, 128, 15,1
Assuming that main memory has an access time of 60ns and cache has an access time of 5ns, calculate the average memory access time for our accesses above.

7. Set Associative Cache
We have a 128-byte 2-way set associative cache with 4 word blocks, using FIFO replacement policy.
Questions:
Sketch layout for 32-bit address.
Calculate TOTAL amount of SRAM needed to implement this cache, assuming write-back policy.
Calculate the hit rate for the following memory (byte) addresses:
0, 32, 33, 64, 8, 80, 18, 128, 15,1
Assuming that main memory has an access time of 60ns and cache has an access time of 5ns, calculate the average memory access time for our accesses above.

12. Full Associative Cache
We have a 128 byte fully-associate cache with 4 word blocks and LRU replacement policy.
Questions:
Sketch layout for 32-bit address.
Calculate TOTAL amount of SRAM needed to implement this cache, assuming write-back policy.
Calculate the hit rate for the following memory (byte) addresses:
0, 32, 33, 64, 8, 80, 18, 128, 15,1
Assuming that main memory has an access time of 60ns and cache has an access time of 5ns, calculate the average memory access time for our accesses above.

17. Exercise #2: Without Forwarding
How many cycles will it take to execute the following code on a 5-stage pipeline without forwarding?
sub $2, $1, $3
and $12, $2, $5
or $13, $6, $2
add $14, $2, $2
sw $15, 100($2)
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18. Exercise #2: Without Forwarding1 2 3 4 5 6 7 8 9 10 11
sub
and or
add sw
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19. Exercise #3: Without Forwarding
How many cycles will it take to execute the following code on a 5-stage pipeline without forwarding?
lw $2, 20($3)
and $12, $2, $5
or $13, $6, $2
add $14, $2, $2
sw $15, 100($2)
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20. Exercise #3: Without Forwarding1 2 3 4 5 6 7 8 9 10 11 lw
and or
add sw
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21. Exercise #4: With Forwarding
How many cycles will it take to execute the following code on a 5-stage pipeline with forwarding?
sub $2, $1, $3
and $12, $2, $5
or $13, $6, $2
add $14, $2, $2
sw $15, 100($2)
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Pipelining

22. Exercise #4: With Forwarding1 2 3 4 5 6 7 8 9 10 11
sub
and or
add sw
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23. Exercise #5: With Forwarding
How many cycles will it take to execute the following code on a 5-stage pipeline with forwarding?
lw $2, 20($3)
and $12, $2, $5
or $13, $6, $2
add $14, $2, $2
sw $15, 100($2)
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24. Exercise #5: With Forwarding1 2 3 4 5 6 7 8 9 10 11 lw
and or
add sw
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25. Exercise #7: Branch Prediction
How many cycles will it take to execute the following code on a 5-stage pipeline with forwarding and branch prediction?
Total instructions = 2 + 1 = 22
Ideal pipeline = 1 = 26 cycles
addi $s0, $zero, 10
Loop: addi $s0, $s0, -1
bne $s0, $zero, Loop
sub $t0, $t1, $t2
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26. Exercise #7: Branch Prediction1 2 3 4 5 6 7 8 9 10 11 IF ID
ALU
MEM WB
addi
bne
addi*
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