Changing dpkg-deb default compression from gzip to lzma for Hardy

[Lars Wirzenius]

On ma, 2007-12-17 at 13:05 +0100, Krzysztof Lichota wrote:
> It is hard to judge best compression using only one package. 

On a lark, I ran a little script that re-compresses the components of
a .deb with the desired compression program, and reports results:

bzip2:
Packages, total count: 22485
Originals, total size: 17467,4 MiB
Repacked, total size: 15944,3 MiB
Size reduction: 1523,06 MiB (8,7 %)
Repacked bigger than original, count: 10777

lzma:
Packages, total count: 22485
Originals, total size: 17467,4 MiB
Repacked, total size: 13167,9 MiB
Size reduction: 4299,46 MiB (24,6 %)
Repacked bigger than original, count: 1421

The above are results for gutsy as of today (or as of about 24 hours
ago, when I last updated my mirror). I chose gutsy, since it is a more
stable target. Please excuse the use LANG=fi_FI formatting of numbers.

Unfortunately, I didn't think of adding code to measure uncompression
speeds. On the other hand, the machine I ran the script on is fairly
fast, so it would not really care about the uncompression speed anyway.
Such a test should be run on a slow machine.

(If anyone wants to duplicate the test, I can provide the script, or the
outputs of the script.)

FWIW, I think it'd be a good thing for Ubuntu to switch from gzip to
lzma. The space savings are quite significant.