Super PI is a computer program

Computer program

A computer program is a sequence of instructions written to perform a specified task with a computer. A computer requires programs to function, typically executing the program's instructions in a central processor. The program has an executable form that the computer can use directly to execute...

 that calculates pi

Pi

' is a mathematical constant that is the ratio of any circle's circumference to its diameter. is approximately equal to 3.14. Many formulae in mathematics, science, and engineering involve , which makes it one of the most important mathematical constants...

 to a specified number of digits after the decimal point—up to a maximum of 32 million. It uses Gauss–Legendre algorithm and is a Windows port of the program used by Yasumasa Kanada

Yasumasa Kanada

is a Japanese mathematician most known for his numerous world records over the past three decades for calculating digits of π. He has set the record 11 of the past 21 times....

 in 1995 to compute pi to 2³² digits.

Significance

Super PI is used by many overclockers

Overclocking

Overclocking is the process of operating a computer component at a higher clock rate than it was designed for or was specified by the manufacturer, but some manufacturers purposely underclock their components to improve battery life. Many people just overclock or 'rightclock' their hardware to...

 to test the performance and stability of their computers. In the overclocking community, the standard program provides a benchmark for enthusiasts to compare "world record" pi calculation times and demonstrate their overclocking abilities. The program can also be used to test the stability of a certain overclock speed. If a computer is able to calculate pi to the 32 millionth place after the decimal without mistake, it is considered to be moderately stable in terms of RAM and CPU. However, longer tests with other CPU/RAM intensive calculation programs will run for hours instead of minutes and may give and/or provide better stress system stability. While Super PI is not the fastest program for calculating pi (see software for calculating π for faster alternatives), it remains very popular in the hardware and overclocking communities.

Credibility concerns

The competitive nature of achieving the best Super PI calculation times led to fraudulent Super PI results, reporting calculation times faster than normal. Attempts to counter the fraudulent results resulted in a modified version of Super PI, with a checksum

Checksum

A checksum or hash sum is a fixed-size datum computed from an arbitrary block of digital data for the purpose of detecting accidental errors that may have been introduced during its transmission or storage. The integrity of the data can be checked at any later time by recomputing the checksum and...

 to validate the results. However, other methods exist of producing inaccurate or fake time results, raising questions about the program's future as an overclocking benchmark.

Super PI utilizes the x86 instruction set. These instructions date all the way back to the 8086 math coprocessor. While they were important for 80386, 80486, and Pentium they became obsolete when 3DNow!

3DNow!

3DNow! is an extension to the x86 instruction set developed by Advanced Micro Devices . It adds single instruction multiple data instructions to the base x86 instruction set, enabling it to perform simple vector processing, which improves the performance of many graphic-intensive applications...

 and Streaming SIMD Extensions

Streaming SIMD Extensions

In computing, Streaming SIMD Extensions is a SIMD instruction set extension to the x86 architecture, designed by Intel and introduced in 1999 in their Pentium III series processors as a reply to AMD's 3DNow! . SSE contains 70 new instructions, most of which work on single precision floating point...

 were released.

The future

Super PI is single threaded

Thread (computer science)

In computer science, a thread of execution is the smallest unit of processing that can be scheduled by an operating system. The implementation of threads and processes differs from one operating system to another, but in most cases, a thread is contained inside a process...

, so its relevance as a measure of performance in the current era of multi-core processors is diminishing quickly. Therefore, Hyper PI has been developed to support multiple threads of Super PI to be run at the same time so you can test stability on multi-core machines. Other multithreaded programs include: IntelBurnTest, Prime95

Prime95

Prime95 is the name of the Microsoft Windows-based software application written by George Woltman that is used by GIMPS, a distributed computing project dedicated to finding new Mersenne prime numbers....

 or OCCT.

External links

• Kanada Laboratory home page with link to ftp site with version of the program for different operating systems. (login as guest)
• Super PI Mod v1.5