Homework-1
1. (20 pts) Explain the dangers of utilizing only a subset of the performance
equation as a performance metric. Use examples if necessary.
2. (20 pts) Computer-A executes the MIPS ISA and computer-B executes the x86
ISA. On average, programs can execute as 1.5 times MIPS instructions as x86
instructions. Computer-A has an average CPI of 1.5 and computer-B an average
CPI of 3. If computer-B runs at a 3GHz clock frequency, what frequency does
computer-A have to run at to be at least as fast as computer B? (assuming that they
run same number of instructions)
3. (20 pts)
i. Calculate the effective CPI of this configuration:
Type CPI for type Frequency
arith/logic 4 40%
load 5 30%
store 3 10%
branch 3 20%
ii. If the clock frequency of this machine is 2.5 GHz, calculate its average MIPS
(millions instructions per second) rate.
4. (20 pts) Which type of instruction is the performance bottleneck for the
program/machine with the following characteristics?
Type CPI for type Frequency
load 4 30%
store 6 10%
add 2 40%
mul 12 8%
div 40 2%
cond
branch
4 8%
uncond
branch
2 2%
5. (20 pts) Considering a computer running a program that requires 250 sec, with
80 sec spent in executing FP (floating point) instructions. By how much is the total
time reduced if the time taken by the FP operations could be reduced by 40% (e.g.,
by employing a faster FP execution unit)?
