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

Krzysztof Lichota krzysiek at lichota.net
Mon Dec 17 14:00:32 GMT 2007


Scott Ritchie napisał(a):
> It's been shown that lzma is, in general, much better.  If we happen to
> find a specific case where it's not, then we can always set that package
> to a non-default by tweaking the dh_builddeb line.

I couldn't find any paper about lzma. But you are right, if it can be
tweaked per-package, then there is always a way out. We just have to
check package sizes in some way.

> I believe lzma has a fairly efficient decompression time.  We should
> note, however, that package installation time is one of the least
> important places to optimize CPU usage - it's not user-interactive, and
> is very frequently done after the user has stopped doing other things.

Why do you think so? I always run system update when I am doing other
things. And I can notice when installing packages starts, although I
have 3 GHz CPU.

> I don't have any data, however from my own personal experience with
> moderately fast broadband it seems like most of my package installation
> time is during downloading rather than unpacking/configure by a very
> wide margin.  A 30% reduction there would require a much larger amount
> of time to unpack to make it not worthwhile.

It is not about time to do update, but the user comfort. If music stops
playing because packages are installed then it is not pleasant user
experience. I have already suggested running background tasks with
ionice
(https://blueprints.launchpad.net/ubuntu/+spec/low-priority-io-for-background-tasks),
running them with nice is also recommended as CPU can be starved, for
example when playing video.

	Krzysztof Lichota




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