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

[Christian Leber]

On Mon, Dec 17, 2007 at 01:05:26PM +0100, Krzysztof Lichota wrote:

> > I've heard that lzma will be included by default in main for Hardy.
> > This is a very good idea.  Changing package build scripts to manually
> > pass lzma compression using dh_builddeb -- -Z lzma would be very
> > tedious, however.  In IRC pitti proposed that we do this centrally -
> > changing the default of dpkg-deb (currently gzip) seems to be the best
> > place for this.

Long ago people claimed that there are problems with upgrades, i guess
to have this clean packages have to pre-depend on dpkg that supports
lzma.

> It is hard to judge best compression using only one package. It is
> possible that for other packages other compression schemes would be
> better. Have you run built other packages? ?The best would be to rebuild
> whole repo with new compression scheme and compare the results, so that
> it does not appear, for example, that packages stop fitting into one CD.

I did a lzma install CD nearly 2 years ago, so there are some numbers
for a whole (breezy) CD:
https://lists.ubuntu.com/archives/ubuntu-devel/2006-January/014246.html

647129088  ->  501211136

> Another thing is decompression time - on some machines the limiting
> resource is CPU, not bandwidth nor disk space and changing compression
> would mean significant burden as packages would be unpacked much longer
> and put more stress on system, making user experience unpleasant.

With a 1 Ghz box you get about 10 MB/s decompressed (of uncompressed
data), so that is hardly a real issue.


Regards,
Christian Leber

-- 
http://rettetdieti.vde-uni-mannheim.de/