Semiconductor & Computer Engineering
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{{title|Microprocessor Performance}} | {{title|Microprocessor Performance}} | ||
The '''performance of a microprocessor''' is a measure of its efficiency in terms of the amount of useful work it accomplishes. | The '''performance of a microprocessor''' is a measure of its efficiency in terms of the amount of useful work it accomplishes. | ||
| + | |||
| + | == Equation == | ||
| + | The performance (time-to-execute) of a certain finite workload is the reciprocal of execution time. | ||
| + | |||
| + | :<math> | ||
| + | P \propto \frac{1}{T_\text{exec}} \qquad \qquad \qquad [\frac{\texttt{programs}}{\texttt{second}}] | ||
| + | </math> | ||
| + | |||
| + | The total execution time, <math>T_\text{exec}</math>, required to execute a specific finite program is. | ||
| + | |||
| + | :<math>T_\text{exec} = \frac{\texttt{IC} \times \texttt{CPI}}{f} \qquad \qquad [\texttt{second}]</math> | ||
| + | |||
| + | Where, | ||
| + | |||
| + | * IC is the [[instruction count]] | ||
| + | * CPI (<math>\frac{1}{I}</math>), the average [[cycles per instructions]]. | ||
| + | * <math>f</math> is the [[clock speed]] | ||
| + | |||
| + | Thus, the performance of a microprocessor can also be defined as. | ||
| + | |||
| + | :<math> | ||
| + | \begin{align} | ||
| + | P &= \frac{f}{\texttt{IC} \times \texttt{CPI}} \\ | ||
| + | \\ | ||
| + | &= \frac{\texttt{IPC} \times f}{\texttt{IC}} | ||
| + | \end{align} | ||
| + | </math> | ||
| + | |||
| + | Note that for the sake of brevity, sometimes the instruction count is omitted when referring to the performance of a fixed portion of code. In other words, when the [[instruction count]] is fixed because the program is not being recompiled, it is sometimes omitted from the equation. However, doing this ignores the fact that recompiling code can have a positive impact on performance. | ||
Revision as of 20:10, 4 January 2019
The performance of a microprocessor is a measure of its efficiency in terms of the amount of useful work it accomplishes.
Equation
The performance (time-to-execute) of a certain finite workload is the reciprocal of execution time.
The total execution time, , required to execute a specific finite program is.
Where,
- IC is the instruction count
- CPI (), the average cycles per instructions.
- is the clock speed
Thus, the performance of a microprocessor can also be defined as.
Note that for the sake of brevity, sometimes the instruction count is omitted when referring to the performance of a fixed portion of code. In other words, when the instruction count is fixed because the program is not being recompiled, it is sometimes omitted from the equation. However, doing this ignores the fact that recompiling code can have a positive impact on performance.