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

[Allan McRae]

On 16/02/10 21:03, Jan de Groot wrote:
> On Tue, 2010-02-16 at 11:21 +0100, Pierre Schmitz wrote:
>> Am Dienstag, 16. Februar 2010 08:51:50 schrieb Jan de Groot:
>>> 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.
>>
>> I just used the default which should be -6.
>>
>>> Note that tighter compressions needs a bigger dictionary size when
>>> unpacking, which can be crap on low-memory systems.
>>
>> Do you have numbers? We could do some testing in qemu with e.g. 128MB RAM
>> etc.. Or maybe have a look at Slackware who are already using xz for their
>> whole repo. According to them you need at least a 486 and 64MB RAM. Does not
>> look like anything we should worry about.
>
> Did some testing with openoffice-base 3.2.0-1-x86_64.tar:
> compression speed:
> gzip:  0m28.945s
> bzip2: 1m21.876s
> xz -1: 0m49.244s
> xz -2: 1m18.444s
> xz -3: 3m34.208s
> xz -6: 4m41.148s
>
> decompression speed:
> gzip:  0m 5.772s
> bzip2: 0m29.433s
> xz -1: 0m13.983s
> xz -2: 0m12.949s
> xz -3: 0m12.706s
> sz -6: 0m11.462s

Is that right?  Decompression gets faster with higher compression ratio?