Re: Bug#278289: ITP: apt-dupdate -- diff-based update of APT's index files
Adrian 'Dagurashibanipal' von Bidder schrieb am Mittwoch, den 27. Oktober 2004:
> On Monday 25 October 2004 23.47, Eduard Bloch wrote:
> > - in difference to apt-pupdate, I do not use chains of small diffs,
> > based on days and managed by the server. Instead, the server provides
> > the patch for a md5sum which contains the diffs between the version
> > of the client and the current one (when the server has data for the
> > old version, of course)
> > - it will be faster on low-speed links since one chunk of data
> > compresses much better than n small chunks. apt-dupdate will use
> > bzip2 instead of gzip.
> How much server load do you anticipate?
The prototype implementation  is quite stupid and needs a while.
Dominant factor is bzip2 speed, calculate with n^2/2*(number of
arches)*(number of branches)*200kB - that is the estimated ammount of
data to be recompress plus base files to be checksummed. Eg. ~40MiB for
stable+testing+unstable (all+i386). I expect less than 1-2 minutes CPU
time for P4-2Ghz, 30days history, 12 arches, unstable+testing.
However, I think about rewritting the current thingie to keep only
patches between the iterations and not store the final patch on the
server. Instead, a CGI script would merge them on demand (and cache the
resulted file somewhere so it may be reused). This would save HD space
and CPU cycles on long term.
> Looking forward to trying this. Is this a tool you plan to deploy on the
> official mirrors/on a public Debian machine/... or is it a tool for people
> with many machines to use on their internal Debian mirror?
You can install it on a mirror and create the diff-chain yourself. It
should be full configurable.
<GyrosGeier> doogie, 25 m/s is pretty fast
<doogie> 40m/s from apache
<doogie> 25m/s is from java
<GyrosGeier> doogie, that's about 8 km/h.
* GyrosGeier ducks
<smurfix> GyrosGeier: Wrong. Other way round please.
<smurfix> 93.6 km/h
<GyrosGeier> smurfix, okay 10 pm
<GyrosGeier> smurfix, but 93 km/h proves my point that it is pretty fast