A lot of small files (e.g. AUTHORS, ChangeLog FWIW: On my system, I have 59M of bz2 files in /usr/share/man and /usr/share/doc. A short script to decompress those and recompress with xz -6e reduced that to 36M. I don't have a comparison for individual file differences.
I posted the short bash scripts at https://gist.github.com/petteyg/96c71fa3c4680552f5c4 On Sun, May 11, 2014 at 4:27 PM, Pacho Ramos <[email protected]> wrote: > El dom, 11-05-2014 a las 19:46 +0200, Michał Górny escribió: > > Hello, developers. > > > > I'd like to raise the following item for discussion: making .xz > > the default compressor used by portage for documentation, man pages > > and info files. That is, the equivalent of: > > > > PORTAGE_COMPRESS=xz > > > > in make.globals. > > > > Rationale: xz-utils is quite widespread nowadays and it is a part > > of @system set. It can achieve better compression ratio than bzip2, > > and faster decompression at the same time. > > > > I have confirmed that both sys-apps/man and sys-apps/man-db can > > handle .xz compressed man pages, and sys-apps/texinfo can handle .xz > > compressed info pages. Major text editors and pagers support .xz > > alike .bz2 (i.e. usually they support both or neither :)). > > > > The additional question is: what preset to use? To help discussing > > this, I'd like to quote the tables from 'man xz': > > > > Preset DictSize CompCPU CompMem DecMem > > -0 256 KiB 0 3 MiB 1 MiB > > -1 1 MiB 1 9 MiB 2 MiB > > -2 2 MiB 2 17 MiB 3 MiB > > -3 4 MiB 3 32 MiB 5 MiB > > -4 4 MiB 4 48 MiB 5 MiB > > -5 8 MiB 5 94 MiB 9 MiB > > -6 8 MiB 6 94 MiB 9 MiB > > -7 16 MiB 6 186 MiB 17 MiB > > -8 32 MiB 6 370 MiB 33 MiB > > -9 64 MiB 6 674 MiB 65 MiB > > > > Preset DictSize CompCPU CompMem DecMem > > -0e 256 KiB 8 4 MiB 1 MiB > > -1e 1 MiB 8 13 MiB 2 MiB > > -2e 2 MiB 8 25 MiB 3 MiB > > -3e 4 MiB 7 48 MiB 5 MiB > > -4e 4 MiB 8 48 MiB 5 MiB > > -5e 8 MiB 7 94 MiB 9 MiB > > -6e 8 MiB 8 94 MiB 9 MiB > > -7e 16 MiB 8 186 MiB 17 MiB > > -8e 32 MiB 8 370 MiB 33 MiB > > -9e 64 MiB 8 674 MiB 65 MiB > > > > I'd like to note here that increasing dictionary size over file size > > does not improve compression. However, the options involved in CompCPU > > may. > > > > Depending on the expected amount of complexity, I'd either go for: > > > > 1) -6e (or -6, the default) -- max CompCPU, reasonable use of memory, > > and dictionary larger than most (or all?) documents that are going to > > be compressed, > > > > 2) -Ne with minimal 'N' for CompCPU==8 and DictSize > filesize -- still > > max compression ratio while keeping lowest memory requirements possible. > > > > Your thoughts? > > > > Per: > https://bugs.gentoo.org/show_bug.cgi?id=372653 > > Looks like bzip2 was still better for small files :/ > > >
