Performance assessment.
Consider two different implementations, M1 and M2 , of the same instruction set. There are three different classes of instructions (A, B, and C) in the instruction set. Implmentation M1 has a clock rate 6Ghz, and M2 has a clock rate of 3GHz. The average number of cycles for each instruction class on M1 and M2 is given in the table below.
The table also contains a summary of average proportion of instruction classes generated by two different compilers, C1 and C2.
Assume that each compiler uses the same number of instructions for a given program but that the instruction mix is as described in the table.
(a) If you purchase M1, which compiler would you use?
(b) If you purchase M2, which compiler would you use?
(c) Which computer and compiler would you purchase if all other criteria were identical, including cost.
Show the decision procedure.
|
Class of instructions
|
CPI on M1
|
CPI on M2
|
C1 usage
|
C2 usage
|
|
A
|
2
|
1
|
50%
|
40%
|
|
B
|
3
|
2
|
25%
|
20%
|
|
C
|
5
|
2
|
25%
|
40%
|