2.9 KiB
LZ4 - Extremely fast compression
LZ4 is lossless compression algorithm, providing compression speed at 400 MB/s per core, scalable with multi-cores CPU. It also features an extremely fast decoder, with speed in multiple GB/s per core, typically reaching RAM speed limits on multi-core systems.
A high compression derivative, called LZ4_HC, is also provided. It trades CPU time for compression ratio.
| Branch | Status |
|---|---|
| master |  |
| dev |  |
| visual |
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. Direct commit to "master" are not permitted.
- Feature branches can also exist, for dedicated tests of larger modifications before merge into "dev" branch.
Benchmarks
The benchmark uses the Open-Source Benchmark program by m^2 (v0.14.3) compiled with GCC v4.8.2 on Linux Mint 64-bits v17. The reference system uses a Core i5-4300U @1.9GHz. Benchmark evaluates the compression of reference Silesia Corpus in single-thread mode.
| Compressor | Ratio | Compression | Decompression |
|---|---|---|---|
| memcpy | 1.000 | 4200 MB/s | 4200 MB/s |
| LZ4 fast (r129) | 1.607 | 680 MB/s | 2220 MB/s |
| LZ4 (r129) | 2.101 | 385 MB/s | 1850 MB/s |
| LZO 2.06 | 2.108 | 350 MB/s | 510 MB/s |
| QuickLZ 1.5.1.b6 | 2.238 | 320 MB/s | 380 MB/s |
| Snappy 1.1.0 | 2.091 | 250 MB/s | 960 MB/s |
| zlib 1.2.8 -1 | 2.730 | 59 MB/s | 250 MB/s |
| LZ4 HC (r129) | 2.720 | 22 MB/s | 1830 MB/s |
| zlib 1.2.8 -6 | 3.099 | 18 MB/s | 270 MB/s |
The raw LZ4 block compression format is detailed within lz4_Block_format.
Compressing an arbitrarily long file or data stream requires multiple blocks. 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 too.