Re: Possible abuse of dpkg-deb -z9 for xz compressed binary packages
On Thu, 25 Sep 2014, Thomas Goirand wrote:
> On 09/02/2014 09:39 PM, Henrique de Moraes Holschuh wrote:
> > For -z9, it is as bad as ~670MiB to
> > compress, and ~65MiB to decompress.
>
> I'd say this really depends on what you do. For what I do (eg: OpenStack
> packages), I don't see how 65MB could be a problem. I do compress with
> -z9, and have no intention to change this, because it makes sense for
> these packages, where the bottleneck for large deployments will more be
> the network transfers than uncompressing on each individual nodes.
OTOH, using -z9 on datasets smaller than the -z8 dictionary size *is* a
waste of memory (I don't know about cpu time, and xz(1) doesn't say anything
on that matter). The same goes for -z8 and datasets smaller than -z7
dictionary size, and so on.
It is rather annoying that xz is not smart enough to detect this and
downgrade the -z level when it is given a seekable file (which it can stat()
and know the full size of beforehand).
--
"One disk to rule them all, One disk to find them. One disk to bring
them all and in the darkness grind them. In the Land of Redmond
where the shadows lie." -- The Silicon Valley Tarot
Henrique Holschuh
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