SPEC CPU®2017 NOT-A-Benchmark Description

NOT-A-Benchmark Name


What do you mean NOT-A-Benchmark?

999.specrand is not timed; it's purpose is primarily as a short, but important, diagnostic.

Although it is not timed, in all other respects, it behaves like an ordinary benchmark.
Therefore the remainder of this description will stop tediously inserting "NOT-A".

Benchmark Author

Cloyce D. Spradling <cloyce+specrand [at] headgear.org>

Benchmark Program General Category

Mine Canary

Benchmark Description

999.specrand is a small harness for the Mersenne Twister algorithm.

The benchmark simply generates a sequence of pseudorandom numbers starting with a known seed. This benchmark is not a timed component of CPU2017; rather, it's there as an indicator of larger problems. Several of the other benchmarks use the specrand code as their PRNG. Thus, a failure in 999.specrand would point out a source of error in those codes as well. This is cheap (in both time and space) insurance.

Input Description

999.specrand's input consists of two numbers: a seed value for the PRNG, and a count of the numbers to generate.

Output Description

The specified number of random numbers are generated and output four times.

The first set is unscaled output from spec_rand() output as a standard floating point number with no precision modifiers (printf '%f' format). The second set is output from spec_rand() scaled to between 1 and 2^31-1 (0x7fffffff, or the maximum positive value that a signed 32-bit integer can hold), and is output as a the original number, the multiplier, and the result as a standard integer (printf '%d' format).

The third set is the output from spec_lrand48() scaled to between 0 and 1 and output in printf '%f' format. The fourth sequence is unscaled output from spec_lrand48() in printf '%d' format.

The PRNG is re-seeded between sequences.

Programming Language


Known portability issues


Sources and Licensing

The benchmark is based on the Mersenne Twister pseudorandom number generator with period 2^19937-1, Copyright 1997 - 2002, Makoto Matsumoto and Takuji Nishimura; Copyright 2005, Mutsuo Saito, under BSD license.

Please see details in the document SPEC CPU®2017 Licenses.


Last updated: $Date: 2020-08-19 18:52:31 -0400 (Wed, 19 Aug 2020) $

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