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Methodology for September 26th, 2001 Article:  iIPC Generation

Dividing a processorís score in a benchmark by its Mhz speed generated our iIPC number.  Remember, this number is not the actual number of Instructions Per Clock Cycle being performedóit is an indicative measure of efficiency.

For example:

According to benchmarks performed by Tomís Hardware (and located here) the Pentium III 1200 has an ALU score of 3392.

The Pentium 4 1800 has an ALU score of 3526.

Dividing the ALU score of the P3 (3392) by its Mhz speed (1200) gives us the iIPC of the P3:  2.83

Performing the same operation on the P4 gives us an iIPC of 1.96. 

As 1.96 is approximately 69% of 2.83, the P4 suffers a 31% iIPC penalty when compared to the P3. 

How We Generated Our Numbers

All numbers used in this review were drawn from other reviews done previously at Anandtech and Tomís Hardware, or are freely available for verfication at www.spec.org.  In no case was a test machine from one review compared to a test machine from another.  Only benchmarks done in the same review by the same reviewer were compared. 

In all cases, our iIPC number was generated by the procedure indicated above.  Also in all cases the iIPC number proved to scale perfectly -- a P4 1.5 Ghz generated the same iIPC as a P4 2 Ghz, etc.

Links to the reviews used are listed below:

Tomís Hardware Guide: Last Passing ManeuverÖ

(Sandra benchmarks, Sysmark2000)

Anandtech:  The Pentium 4 1.4 and 1.5 Ghz

(Sysmark2000)

SPEC.ORG:  Submitted SPECINT 2000 Results

(SpecINT2000)

Explanation of Benchmark Choices:

The benchmarks demonstrated in this article were chosen for several reasons.  All of them are processor-oriented, rather than stressing other subsystems such as video card speed or memory bandwidth.  All of them are easily verifiable and duplicatable for those wishing to check our research or conclusions.

In addition, all of them are recognized by the hardware community as commonly used benchmarks and one of them (Sysmark 2000) represents a suite of commonly used programs in the business and office space. 

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