d097bf93f8
Only enabled when searching forward. note : it slighly improves compression ratio, but measurably decreases speed. Trade-off to analyse. |
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LZ4 - Extremely fast compression
LZ4 is lossless compression algorithm, providing compression speed at 400 MB/s per core, scalable with multi-cores CPU. It features an extremely fast decoder, with speed in multiple GB/s per core, typically reaching RAM speed limits on multi-core systems.
Speed can be tuned dynamically, selecting an "acceleration" factor which trades compression ratio for more speed up. On the other end, a high compression derivative, LZ4_HC, is also provided, trading CPU time for improved compression ratio. All versions feature the same decompression speed.
LZ4 library is provided as open-source software using BSD 2-Clause license.
| Branch | Status |
|---|---|
| master |   |
| dev |  |
Branch Policy:
- The "master" branch is considered stable, at all times.
- The "dev" branch is the one where all contributions must be merged before being promoted to master.
- If you plan to propose a patch, please commit into the "dev" branch, or its own feature branch. Direct commit to "master" are not permitted.
Benchmarks
The benchmark uses lzbench, from @inikep compiled with GCC v7.3.0 on Linux 64-bits (Debian 4.15.17-1). The reference system uses a Core i7-6700K CPU @ 4.0GHz. Benchmark evaluates the compression of reference Silesia Corpus in single-thread mode.
| Compressor | Ratio | Compression | Decompression |
|---|---|---|---|
| memcpy | 1.000 | 13100 MB/s | 13100 MB/s |
| LZ4 default (v1.8.2) | 2.101 | 730 MB/s | 3900 MB/s |
| LZO 2.09 | 2.108 | 630 MB/s | 800 MB/s |
| QuickLZ 1.5.0 | 2.238 | 530 MB/s | 720 MB/s |
| Snappy 1.1.4 | 2.091 | 525 MB/s | 1750 MB/s |
| Zstandard 1.3.4 -1 | 2.877 | 470 MB/s | 1380 MB/s |
| LZF v3.6 | 2.073 | 380 MB/s | 840 MB/s |
| zlib deflate 1.2.11 -1 | 2.730 | 100 MB/s | 380 MB/s |
| LZ4 HC -9 (v1.8.2) | 2.721 | 40 MB/s | 3920 MB/s |
| zlib deflate 1.2.11 -6 | 3.099 | 34 MB/s | 410 MB/s |
LZ4 is also compatible and well optimized for x32 mode, for which it provides some additional speed performance.
Installation
make
make install # this command may require root access
LZ4's Makefile supports standard Makefile conventions,
including staged installs, redirection, or command redefinition.
It is compatible with parallel builds (-j#).
Documentation
The raw LZ4 block compression format is detailed within lz4_Block_format.
To compress an arbitrarily long file or data stream, multiple blocks are required. Organizing these blocks and providing a common header format to handle their content is the purpose of the Frame format, defined into lz4_Frame_format. Interoperable versions of LZ4 must respect this frame format.
Other source versions
Beyond the C reference source, many contributors have created versions of lz4 in multiple languages (Java, C#, Python, Perl, Ruby, etc.). A list of known source ports is maintained on the LZ4 Homepage.