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Continuing the washer/dryer/folding example from lecture, suppose that the washer takes 20 minutes, the dryer 40, and folding 15.

Question 1: (see above) If we replace the dryer with two dryers, leaving clothes in the first for 20 minutes and then moving them to the second for another 20 minutes, we would

  1. increase latency

  2. increase throughput

  3. decrease latency

  4. decrease throughput

Question 2: (see above) Which of the following would be an example of a control dependency?

  1. You only want to wash the rest of your dry-clean-only shirts if the first one looked OK after being washed

  2. You want to put the same bright red rag in every load of wash to dye your clothes pinkish

  3. Your wiring is old enough that you'll blow a fuse if you run the washer and dryer at the same time

  4. You have to share your washer with other people, and they're using it right now

Question 3: (see above) Which of the following would be an example of a data dependency?

  1. You only want to wash the rest of your dry-clean-only shirts if the first one looked OK after being washed

  2. You want to put the same bright red rag in every load of wash to dye your clothes pinkish

  3. Your wiring is old enough that you'll blow a fuse if you run the washer and dryer at the same time

  4. You have to share your washer with other people, and they're using it right now

The first version of the pipelined addq machine we looked at in class would give the wrong result for the following code

addq %r8, %r9
addq %r9, %r10

Question 4: (see above) Which of the following programs would also give the wrong results?
Select all that apply

  1. addq %r8, %r9; addq %r10, %r9

  2. addq %r9, %r8; addq %r9, %r10

  3. addq %r9, %r8; addq %r10, %r9

  4. addq %r10, %r9; addq %r8, %r9

  5. addq %r9, %r10; addq %r9, %r8

  6. addq %r10, %r9; addq %r9, %r8

Question 5: (see above) We discussed fixing this by adding nop instructions and by having the hardware stall. If we can add stalling to the hardware without changing the hardware clock speed,

  1. manually adding nops where needed would be faster

  2. hardware stalling would be faster

  3. which one would be faster depends on the particular situation

  4. they both have equivalent speed

Question 6: Which is most important for a processor to seem fast to the end user?

  1. high latency

  2. low latency

  3. high throughput

  4. low throughput

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