The basic performance equation can therefore be written in terms of
- instruction count (the number of instructions executed by the program),
- CPI (clock cycles per instruction), and
- clock cycle time.
or, since the clock rate is the inverse of clock cycle time:
CPU times = Instruction count × CPI × Clock cycle time
CPU times = ( Instruction count × CPI ) / Clock rate
Computing CPU Time
Consider two different implementations, P1 and P2, of the same instruction set architecture. There are three classes of instructions, A, B, and C. The clock rate and CPI of each implementation are given in the following table:
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Given a program with 104 instructions divided into classes as follows: 30% class A, 30% class B, and 40% class C, which implementation is faster?
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