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src.rivoreo.one / lz4 / 24b9c485db34743f83496038d61598d41c3c497e
commit24b9c485db34743f83496038d61598d41c3c497e[log] [download]
authorYann Collet <cyan@fb.com>Sun May 06 16:47:31 2018 -0700
committerYann Collet <cyan@fb.com>Sun May 06 16:53:33 2018 -0700
tree2c95ebb555b60f7793aa28337bc230f8cd1e993e
parentcdb0275b7f7513e13a05c27adea658614c0174d9 [diff]
small PA optimization

which measurably improves speed
on levels 9+
1 file changed
tree: 2c95ebb555b60f7793aa28337bc230f8cd1e993e
  1. .gitattributes
  2. .gitignore
  3. .travis.yml
  4. INSTALL
  5. LICENSE
  6. Makefile
  7. NEWS
  8. README.md
  9. appveyor.yml
  10. circle.yml
  11. contrib/
  12. doc/
  13. examples/
  14. lib/
  15. programs/
  16. tests/
  17. visual/
README.md

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.

BranchStatus
masterBuild Status Build status coverity
devBuild Status Build status

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.

CompressorRatioCompressionDecompression
memcpy1.00013100 MB/s13100 MB/s
LZ4 default (v1.8.2)2.101730 MB/s3900 MB/s
LZO 2.092.108630 MB/s800 MB/s
QuickLZ 1.5.02.238530 MB/s720 MB/s
Snappy 1.1.42.091525 MB/s1750 MB/s
Zstandard 1.3.4 -12.877470 MB/s1380 MB/s
LZF v3.62.073380 MB/s840 MB/s
zlib deflate 1.2.11 -12.730100 MB/s380 MB/s
LZ4 HC -9 (v1.8.2)2.72140 MB/s3920 MB/s
zlib deflate 1.2.11 -63.09934 MB/s410 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.