Performance definition

Performance definition

by Razvan Vass -
Number of replies: 5

Hello!

I have a question regarding the performance. Is this Wikipedia page wrong?
Cycles per instruction - Wikipedia

More specific this sentence: "cycles per instruction (aka clock cycles per instruction, clocks per instruction, or CPI) is one aspect of a processor's performance".

After the course and after the lab I understood that it is wrong, but I still think it is a method of measuring performance because it doesn't make any sense to not be.

Thank you.

In reply to Razvan Vass

Re: Performance definition

by Ayesha Afzal -
Dear Razvan,

During one of the tutorials, it was already being discussed that million instructions per second (MIPS) is another performance metric.
It was also discussed why, in comparison to other performance metrics, MIPS is not a good performance metric, as was questioned in the first assignment (#0).

Best regards,
Ayesha
In reply to Ayesha Afzal

Re: Performance definition

by Razvan Vass -
Ok, but my question was not related to MIPS, it was to CPI.
And my question was not related to be a good or bad performance.

If you can explain me what is the connection with what I asked please help me discover.

Thank you.
In reply to Razvan Vass

Re: Performance definition

by Georg Hager -

MIPS stands for "Million Instructions Per Second," while CPI means "Cycles Per Instruction." Apart from a scaling factor, one is the reciprocal of the other. 

In reply to Georg Hager

Re: Performance definition

by Razvan Vass -
I'm sorry but still I don't understand.

Is CIP one aspect of a processor's performance?
In reply to Razvan Vass

Re: Performance definition

by Georg Hager -
Yes it is, but Wikipedia has an unfortunate wording since CPI is the **reciprocal** of instructions per time unit. And, as discussed in the lecture, there are better ways to characterize performance because the number of instructions is not a good metric for "work."