91 lines
4.1 KiB
Markdown
91 lines
4.1 KiB
Markdown
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LZ4 - Extremely fast compression
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================================
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LZ4 is lossless compression algorithm,
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providing compression speed at 400 MB/s per core,
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scalable with multi-cores CPU.
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It features an extremely fast decoder,
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with speed in multiple GB/s per core,
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typically reaching RAM speed limits on multi-core systems.
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Speed can be tuned dynamically, selecting an "acceleration" factor
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which trades compression ratio for more speed up.
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On the other end, a high compression derivative, LZ4_HC, is also provided,
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trading CPU time for improved compression ratio.
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All versions feature the same decompression speed.
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LZ4 library is provided as open-source software using BSD license.s
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|Branch |Status |
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|------------|---------|
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|master | [![Build Status][travisMasterBadge]][travisLink] [![Build status][AppveyorMasterBadge]][AppveyorLink] [![coverity][coverBadge]][coverlink] |
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|dev | [![Build Status][travisDevBadge]][travisLink] [![Build status][AppveyorDevBadge]][AppveyorLink] |
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[travisMasterBadge]: https://travis-ci.org/Cyan4973/lz4.svg?branch=master "Continuous Integration test suite"
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[travisDevBadge]: https://travis-ci.org/Cyan4973/lz4.svg?branch=dev "Continuous Integration test suite"
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[travisLink]: https://ci.appveyor.com/project/YannCollet/lz4
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[AppveyorMasterBadge]: https://ci.appveyor.com/api/projects/status/v6kxv9si529477cq/branch/master?svg=true "Visual test suite"
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[AppveyorDevBadge]: https://ci.appveyor.com/api/projects/status/v6kxv9si529477cq/branch/dev?svg=true "Visual test suite"
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[AppveyorLink]: https://ci.appveyor.com/project/YannCollet/lz4
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[coverBadge]: https://scan.coverity.com/projects/4735/badge.svg "Static code analysis of Master branch"
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[coverlink]: https://scan.coverity.com/projects/4735
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> **Branch Policy:**
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> - The "master" branch is considered stable, at all times.
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> - The "dev" branch is the one where all contributions must be merged
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before being promoted to master.
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> + If you plan to propose a patch, please commit into the "dev" branch,
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or its own feature branch.
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Direct commit to "master" are not permitted.
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Benchmarks
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-------------------------
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The benchmark uses the [Open-Source Benchmark program by m^2 (v0.14.3)]
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compiled with GCC v4.8.2 on Linux Mint 64-bits v17.
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The reference system uses a Core i5-4300U @1.9GHz.
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Benchmark evaluates the compression of reference [Silesia Corpus]
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in single-thread mode.
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| Compressor | Ratio | Compression | Decompression |
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| ---------- | ----- | ----------- | ------------- |
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| memcpy | 1.000 | 4200 MB/s | 4200 MB/s |
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|**LZ4 fast 17 (r129)**| 1.607 |**690 MB/s** | **2220 MB/s** |
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|**LZ4 default (r129)**|**2.101**|**385 MB/s** | **1850 MB/s** |
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| LZO 2.06 | 2.108 | 350 MB/s | 510 MB/s |
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| QuickLZ 1.5.1.b6 | 2.238 | 320 MB/s | 380 MB/s |
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| Snappy 1.1.0 | 2.091 | 250 MB/s | 960 MB/s |
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| LZF v3.6 | 2.073 | 175 MB/s | 500 MB/s |
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| zlib 1.2.8 -1 | 2.730 | 59 MB/s | 250 MB/s |
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|**LZ4 HC (r129)** |**2.720**| 22 MB/s | **1830 MB/s** |
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| zlib 1.2.8 -6 | 3.099 | 18 MB/s | 270 MB/s |
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Documentation
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-------------------------
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The raw LZ4 block compression format is detailed within [lz4_Block_format].
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To compress an arbitrarily long file or data stream, multiple blocks are required.
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Organizing these blocks and providing a common header format to handle their content
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is the purpose of the Frame format, defined into [lz4_Frame_format].
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Interoperable versions of LZ4 must respect this frame format.
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Other source versions
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-------------------------
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Beyond the C reference source,
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many contributors have created versions of lz4 in multiple languages
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(Java, C#, Python, Perl, Ruby, etc.).
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A list of known source ports is maintained on the [LZ4 Homepage].
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[Open-Source Benchmark program by m^2 (v0.14.3)]: http://encode.ru/threads/1371-Filesystem-benchmark?p=34029&viewfull=1#post34029
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[Silesia Corpus]: http://sun.aei.polsl.pl/~sdeor/index.php?page=silesia
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[lz4_Block_format]: lz4_Block_format.md
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[lz4_Frame_format]: lz4_Frame_format.md
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[LZ4 Homepage]: http://www.lz4.org
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