You can also perform the same comparison between bzip2 and lzma. The bzip2 man page shows that a bzip2 archive requires roughly 3700kB of memory when uncompressing if it has been compressed with "-9" force.
On the other side, the xz man page tells that a xz archive requires roughly 3 MB of memory when uncompressing if it has been compressed with "-4" force. With the below example, compared to the bzip2 compression method, the lzma method : - saves up to 18% of archive size - requires less memory for decompression. Maybe we could imagine the below rules for packaging deb archives : - "xz -1e" by default - "xz -4e" for archives which were previously compressed with bzip2 - "xz -9e" for archives whose application requires a lot of memory at runtime Below are the result of the compression ratios of bzip2 and lzma : ----------------------------------------------------------------- j@dt:~/tmp$ 7z x /var/cache/apt/archives/linux-image-2.6.32-42-generic_2.6.32-42.95_amd64.deb 7-Zip 9.04 beta Copyright (c) 1999-2009 Igor Pavlov 2009-05-30 p7zip Version 9.04 (locale=fr_FR.UTF-8,Utf16=on,HugeFiles=on,2 CPUs) Processing archive: /var/cache/apt/archives/linux- image-2.6.32-42-generic_2.6.32-42.95_amd64.deb Extracting control.tar.gz Extracting data.tar.bz2 Everything is Ok Files: 2 Size: 31896829 Compressed: 31897022 j@dt:~/tmp$ bunzip2 -c data.tar.bz2 > data.tar j@dt:~/tmp$ bzip2 -c9 data.tar > data.tar.bz2-9 j@dt:~/tmp$ lzma -c4 data.tar > data.tar.lzma-4 j@dt:~/tmp$ xz -c4e data.tar > data.tar.xz-4e j@dt:~/tmp$ xz -c1e data.tar > data.tar.xz-1e j@dt:~/tmp$ lzma -c1 data.tar > data.tar.lzma-1 j@dt:~/tmp$ ls -lk total 289852 -rw-r--r-- 1 j j 91 2012-07-25 18:44 control.tar.gz -rw-r--r-- 1 j j 117370 2012-08-19 14:52 data.tar -rw-r--r-- 1 j j 31059 2012-07-25 18:44 data.tar.bz2 -rw-r--r-- 1 j j 31059 2012-08-19 15:02 data.tar.bz2-9 -rw-r--r-- 1 j j 29946 2012-08-19 15:28 data.tar.lzma-1 -rw-r--r-- 1 j j 26193 2012-08-19 15:10 data.tar.lzma-4 -rw-r--r-- 1 j j 28509 2012-08-19 15:27 data.tar.xz-1e -rw-r--r-- 1 j j 25605 2012-08-19 15:14 data.tar.xz-4e j@dt:~/tmp$ ----------------------------------------------------------------- -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1037193 Title: deb package archive should use "lzma -1" or "xz -1e" compression by default To manage notifications about this bug go to: https://bugs.launchpad.net/dpkg/+bug/1037193/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
