1) Suppose machine A executes a program with an average CPI of 2.3.
Consider another machine B
(with same instruction set and a better compiler) that executes the same program with 20% less
instructions and with a CPI of 1.7 at 1.2 GHz.
What should be the clock rate of A so that the two machines have the same performance?
2) Consider IC = 50,000,000; average CPI = 2.7 and clock rate = 2.0GHz
Suppose we use a new compiler on the same program for which:
New IC = 40,000,000
New CPI = 3.0 (New compiler is using more complex instructions)
Also, we have faster CPU implementation, with clock rate = 2.5GHz
Find speedup.
3) Consider an implementation of a ISA where the instructions can be classified into four types, with
CPI values of 1, 2, 3 and 4 respectively.
Two code sequences have the following instructions counts:
Code Sequence ICtype1 ICtype2 ICtype3 ICtype4
CS-1 20 15 5 2
CS-2 10 12 10 4
Compare CS-1 and CS-2 on basis of CPI
4) Suppose for an implementation of a RISC ISA, there are four types, with their frequency of
occurrence (for a typical mix of programs) and CPI as shown in the table below.
Type Frequency CPI
Load 20% 4
Store 8% 3
ALU 60% 1
Branch 12% 2
Find CPI of the program.
5) Suppose that a program is running on a machine with the following instruction types, CPI
values and the frequencies of occurrence.
The designer gives two options:
(a) Reduce CPI of instruction type A to 1.1, and
(b) reduce CPI of instruction type B to 1.6. Which one is better?
Type CPI Frequency
A 1.3 60%
B 2.2 10%
C 2.0 30%
