Package: xz-utils Version: 5.6.0-0.2 Severity: wishlist After upgrading xz-utils from 5.4.5-0.3 to 5.6.0-0.2, the compression ratio with "xz -9" has decreased. For instance, on 3 files:
Old 118822308 146463040 157197172 New 121120576 148930624 161255000 It took me some time to figure out. This is the reason: /usr/share/doc/xz-utils/NEWS.gz 5.6.0 (2024-02-24) [...] * xz: - Multithreaded mode is now the default. This improves compression speed and creates .xz files that can be decompressed in multithreaded mode. The downsides are increased memory usage and slightly worse compression ratio. [...] Using -T1 restores the old behavior. Since this affects what the user gets and is some kind of regression, this should be announced in NEWS.Debian, IMHO. Note also that this change might affect diffs between .xz files (e.g. after something is appended to the uncompressed file), though I have not checked. -- System Information: Debian Release: trixie/sid APT prefers unstable-debug APT policy: (500, 'unstable-debug'), (500, 'stable-updates'), (500, 'stable-security'), (500, 'stable-debug'), (500, 'proposed-updates-debug'), (500, 'unstable'), (500, 'testing'), (500, 'stable'), (1, 'experimental') Architecture: amd64 (x86_64) Kernel: Linux 6.6.15-amd64 (SMP w/16 CPU threads; PREEMPT) Locale: LANG=C.UTF-8, LC_CTYPE=C.UTF-8 (charmap=UTF-8), LANGUAGE not set Shell: /bin/sh linked to /usr/bin/dash Init: systemd (via /run/systemd/system) LSM: AppArmor: enabled Versions of packages xz-utils depends on: ii libc6 2.37-15.1 ii liblzma5 5.6.0-0.2 xz-utils recommends no packages. xz-utils suggests no packages. -- no debconf information -- Vincent Lefèvre <vinc...@vinc17.net> - Web: <https://www.vinc17.net/> 100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/> Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)