Xz
xz[1] compress or decompress (unxz) .xz and .lzma files but xz compresses by default to xz format.
xz support multi-threaded compression (-T flag)[2] since 2014, version 5.2.0. [3], as of 2019 threaded decompression hasn’t been implemented yet. [4]. Number of threads can be less that defined is file is not big enough for threading with the given settings or if using more threads would exceed the memory usage limit. [5]
xz has replaced gzip in some uses case such as in Arch Linux packages because it decreases package size about 30% smaller depending on the data.
Contents
Options
--keepOnce the target file has been successfully closed, the source file is removed unless --keep was specified
Commands
xz --info-memory
xz --info-memory Total amount of physical memory (RAM): 515,654 MiB (540,702,060,544 B) Memory usage limit for compression: Disabled Memory usage limit for decompression: Disabled
- Use
--verboseoption twice to get extra information about compression, such us number of threads to use or memory required. It can impact xz performance.
xz -T0 --verbose --verbose file_to_compress
xz: Filter chain: --lzma2=dict=8MiB,lc=3,lp=0,pb=2,mode=normal,nice=64,mf=bt4,depth=0 xz: Using up to 48 threads. xz: 7,925 MiB of memory is required. The limiter is disabled. xz: Decompression will need 9 MiB of memory. .../...
Examples
- Test integrity:
xz -tv linux-3.18.19.tar.xz - Compress data from
stdin:echo "DATA TO COMPRESS" | xz --verbose > file.xz - Compress all files in directory and subdirectory except already compresed (
.xz) using all CPUs (-T0):
find . -type f -not -name \*.xz -exec xz -T0 --verbose \{\} \;
Activities
- Compress your data using gzip and xz and compare sizes
- Compare sizes of Linux Kernel source code depending of compression tools used: https://mirrors.edge.kernel.org/pub/linux/kernel/v5.x/
- Compress your file using single thread
xzand compress same file using all your available threadsxz -T0 - Compress your file with
xz -T0and verify that you are using all your threads with htop
See also
- Data compression: LZMA,
xz, unxz,xz -t, xz -q, xz -T0, xz -9, zstd, Igor Pavlov zstd[6] compression utility released in 2015 which includes parallel (multi-threaded) implementations of both compression and decompressioncp,dd,sftp,scp,rsync,casync,mv,fio,ln,docker cp, kubectl cp,minikube cp,multipass transfer,Copy-Item,Xcopy- Intel QAT (QuickAssist Technology): https://software.intel.com/en-us/articles/how-intel-quickassist-technology-accelerates-nfv-use-cases
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