Using zsync for .deb downloads: initial benchmark results

[Steve Langasek]

On Fri, Jul 17, 2009 at 05:11:14PM +0300, Lars Wirzenius wrote:
> pe, 2009-07-17 kello 12:20 +0100, Matt Zimmerman kirjoitti:
> > On Tue, Jul 14, 2009 at 07:19:31PM +0300, Lars Wirzenius wrote:
> > > * rsyncable: This makes it easier for zsync to do magic things with gzip,
> > >   by recompressing the gzipped tarballs within the .deb files with gzip
> > >   --rsyncable. This provies a lot of improvement. Saving a quarter of
> > >   the bandwidth is already fairly significant, especially since the
> > >   size impact on the .debs is less than 1%. 
> ...
> > > * rsyncable3: Some packages use lzma or bzip2 compression of the
> > >   tarballs within the .deb. This benchmark converts those to be
> > >   compressed with gzip --rsyncable. This improves things a bit compared
> > >   to just rsyncable, at a 17% increase in size compared to rsyncable.
> > >   Because most of the packages using lzma are OpenOffice.org related,
> > >   it is probably not realistic to make them use gzip --rsyncable due
> > >   to CD size limits, but it might be possible to use them for updates
> > >   that don't get put into CDs.

> > Do you have figures for how much the size of the .debs increased in each of
> > these scenarios?  We obviously need to take this into account as a cost of
> > the change, particularly considering the limitations on the size of the
> > ISOs.

> rsyncable: just under 1%. rsyncable3: about 18%.

> Thus, using --rsyncable should be doable for the CD, but re-compressing
> things with gzip instead of lzma or bzip2 is not.

Over a 700MB CD, 1% is 7MB.  That amounts to a full language dropped from
the alternate CD.

-- 
Steve Langasek                   Give me a lever long enough and a Free OS
Debian Developer                   to set it on, and I can move the world.
Ubuntu Developer                                    http://www.debian.org/
slangasek at ubuntu.com                                     vorlon at debian.org