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Standard Performance Evaluation Corporation

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SPEC CPU2000 Benchmark Description File

Benchmark Name


Benchmark Author

Jean-Loup Gailly <>

Benchmark Program General Category


Benchmark Description

gzip (GNU zip) is a popular data compression program written by Jean-Loup Gailly <> for the GNU project. `gzip' uses Lempel-Ziv coding (LZ77) as its compression algorithm.

SPEC's version of gzip performs no file I/O other than reading the input. All compression and decompression happens entirely in memory. This is to help isolate the work done to just the CPU and the memory subsystem.

Input Description

164.gzip's reference workload has five components: a large TIFF image, a webserver log, a program binary, random data, and a source tar file. With the exception of the random data, these components were selected as a reasonably representative set of things that gzip might be most often used on. The random data is present to test gzip's worst-case behavior.

Each input set is compressed and decompressed at several different blocking factors ("compression levels"), with the end result of the process being compared to the original data after each step.

Output Description

The output files provide a brief outline of what the benchmark is doing as it runs. Output sizes for each compression and decompression are printed to facilitate validation, and the results of decompression are compared with the input data to ensure that they match.

Programming Language


Known portability issues

The header file "io.c" is not automatically included. If your compiler needs this header file, define NEED_IO_H.


Last updated: 5 October 1999