Benchmarks

These benchmarks are written using Google Benchmark.

Repetitions

To increase the number of times each benchmark iteration is run use:

--benchmark_repetitions=20

Filters

To filter out which benchmarks are performed use:

--benchmark_filter="adler32*"

There are two different benchmarks, micro and macro.

Benchmark benchmark_zlib

These are microbenchmarks intended to test lower level subfunctions of the library.

Benchmarks include implementations of: - Adler32 - CRC - 256 byte comparisons - SIMD accelerated “slide hash” routine

By default these benchmarks report things on the nanosecond scale and are small enough to measure very minute differences.

Alternative zlib library

To benchmark against an alternative zlib-compatible library, use the ZLIB_LIBRARY CMake argument. When set, only the public API benchmarks are built:

cmake -S . -B build-alt \
    -DZLIB_COMPAT=ON \
    -DBUILD_SHARED_LIBS=OFF \
    -DBUILD_TESTING=ON \
    -DWITH_BENCHMARKS=ON \
    -DCMAKE_BUILD_TYPE=Release \
    -DWITH_RUNTIME_CPU_DETECTION=OFF \
    -DZLIB_LIBRARY=/path/to/libz.a

Benchmark benchmark_zlib_apps

These benchmarks measure applications of zlib as a whole. Currently the only examples are PNG encoding and decoding. The PNG encode and decode tests leveraging procedurally generated and highly compressible image data.

Additionally, a test called png_decode_realistic that will decode any RGB 8 BPP encoded set of PNGs in the working directory under a directory named “test_pngs” with files named {0..1}.png. If these images do not exist, they will error out and the benchmark will move on to the next set of benchmarks.

benchmark_zlib_apps_alt

The user can compile a comparison benchmark application linking to any zlib-compatible implementation of his or her choosing.