Re: Status of deb(5) format support in Debian
On Thu, Aug 01, 2013 at 05:21:01PM +0100, Dmitrijs Ledkovs wrote:
> On 1 August 2013 16:21, Adam Borowski <kilobyte@angband.pl> wrote:
> > On Thu, Aug 01, 2013 at 03:52:38PM +0100, Dmitrijs Ledkovs wrote:
> >> On 1 August 2013 15:40, Adam Borowski <kilobyte@angband.pl> wrote:
> >> > On Wed, Jul 31, 2013 at 06:24:32PM +0200, Guillem Jover wrote:
> >> >> [...] in preparation to add non-gzip compression support for control.tar
> >> >
> >> > May I ask why would you want that?
> >> >
> >> > There's a lot of extra complexity, incompatibility with existing tools,
> >> > added moving parts... and I'm not aware of any gain.
> >> >
> >> > xz, while vastly superior to gzip and bzip2 for bulk data, suffers from
> >> > slow start: for files a few tens of kilobytes or smaller, xz compresses
> >> > worse than gzip. Thus, control.tar.xz is hardly ever a good idea.
> >> >
> >> > On the other hand, control files compress pretty well, so you want _some_
> >> > form of compression. For files this small, CPU costs are totally
> >> > negligible.
> >> >
> >> > Thus, with .tar.gz being either the best or very close to the best,
> >> > what would be the point of this change?
> >> >
> >>
> >> For debian-installer (et. al. components) at the moment control.tar.gz
> >> is often larger than data.tar.xz since "templates" are very long and
> >> include a lot of translations.
> >
> > Hmm... indeed, some udebs have monstrous control tarballs, the biggest one
> > being 1167360 bytes long (uncompressed).
> >
> >> So for that package group it's valuable to have control.tar.xz.
> >
> > Still, total gains for all udebs (jessie netinst amd64) are only 1.22MB.
> > Should I try this for regular debs?
> >
>
> libc6 compressed control.tar.gz is 66kB
>
> It has uncompressed 111kB symbols, 68.5kB templates.....
Aaaand the winner is:
ns3-doc
tar: 10199040
gz: 2306528
xz: 1945456
Looks like I underestimated packages with massive control files.
On the other hand, the total gain for all regular debs in the archive is
just 14MB (out of 58GB amd64 unstable main+contrib+non-free). I'd still
say it's not worth having to modify every tool, but it's up to you to
decide.
In any case, here's the raw data:
http://angband.pl/tmp/deb-control.sql
http://angband.pl/tmp/udeb-control.sql
--
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