[arch-dev-public] [PATCH] Support xz compressed packages

[Jan de Groot]

On Mon, 2010-02-15 at 22:15 +0100, Pierre Schmitz wrote:
> Am Montag, 15. Februar 2010 19:36:41 schrieb Jan de Groot:
> > > if not it's not an improvement and we should think about pbzip that
> > > now
> > > supports tar interaction and pipes! 
> > 
> > Depends on the compression level. It's slower than gzip compression, but
> > faster than bzip2 if you don't select the highest compression level. I
> > guess you'll save more time uploading an xz-compressed openoffice
> > package than you'll lose by compressing it with that.
> 
> Indeed. E.g. I just compiled Qt and package size went down from 34 MB to 25 
> MB. This saves me about 10 MByte upload for each arch. I didn't note any 
> massive increase in compression time compared to compile and upload time.
> 
> Sure there are edge cases like big icon packs which wont compress well anyway. 
> But in general the benefit of the way smaller packages is rally worth it. And 
> you don't have to forget that you only compress a package once; but it's 
> uploaded and downloaded many, many times.

What's the compression rate used in your test? I've seen benchmarks for
an older version of xz-utils (I think it was called lzma-utils). In that
benchmark the most simple compression level was faster and smaller than
gzip -9, and bzip2 was outperformed anyways.

Note that tighter compressions needs a bigger dictionary size when
unpacking, which can be crap on low-memory systems.