MC48 Homework 1 (Fall 1998)

Due: September 15, 1998

1. Do exercises 1.51-1.53 from pages 49-50. (You will need to refer to page 48.)
2. From the data on page 73, how much higher is the CPI of the 200 MHz Pentium system than the CPI of the 100 MHz Pentium system on the SPECint95 workload? On the SPECfp95 workload? (Ignore the issue that each SPEC ratio is actually a geometric mean over different programs; pretend that a single int workload and a single fp workload is represented.)
3. Do exercises 2.31-2.32 on page 96.
4. You are the manager of a microprocessor design team. Your microprocessor currently has an average CPI of 1.5. The software that will run on your microprocessor already exists and is fixed: it will not be rewritten or recompiled in response to your design decisions. One of the members of your design team suggests a change that will reduce the CPI of multiply instructions from 3 to 2 (and leave the CPI of other instructions unchanged). However, it will require lengthening the cycle time by 5%. You need to decide whether this change is desirable or not.
   1. In order to make this decision, you need to ask the software experts for one specific numerical piece of information about the software that will be run on the microprocessor. What is this one number that is key to your decision? (Remember: it is to be a fact about the software itself, not about how the software will run on the hardware.)
   2. How large does that number need to be for the design change to be a good idea? (This assumes that a larger number is more favorable for the design change. If the reverse is true, state how small the number needs to be for the design change to be a good idea.)

Instructor: Max Hailperin