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Re: Possible abuse of dpkg-deb -z9 for xz compressed binary packages



2014-09-03 14:49 GMT+09:00 Andrey Rahmatullin <wrar@debian.org>:
> On Wed, Sep 03, 2014 at 07:32:49AM +0200, Christian PERRIER wrote:
>> At the time, we (font team) decided to go with z9, the fact that
>> packages were arch:all (and therefore that the memory cost of
>> compression had only an impact on the machine of the developer who
>> builds packages), was a strong argument to go with z9.
>>
>> Of course, if we go to source only uploads for arch:all, we'll
>> reconsider this and eventually revert to default settings.
>>
>> (still, this memory impact has never been one on the good old Dell
>> Poweredge 2650 that sits in my garage and builds most of the font
>> packages I upload..... Of course, it is not a buildd that builds
>> hundreds of packages a day)
> Decompression costs were mentioned too, and they always matter (if they
> are significant). Does anyone have numbers about them?

>From xz(1),

                     Preset   DictSize   CompCPU   CompMem   DecMem
                       -0     256 KiB       0        3 MiB    1 MiB
                       -1       1 MiB       1        9 MiB    2 MiB
                       -2       2 MiB       2       17 MiB    3 MiB
                       -3       4 MiB       3       32 MiB    5 MiB
                       -4       4 MiB       4       48 MiB    5 MiB
                       -5       8 MiB       5       94 MiB    9 MiB
                       -6       8 MiB       6       94 MiB    9 MiB
                       -7      16 MiB       6      186 MiB   17 MiB
                       -8      32 MiB       6      370 MiB   33 MiB
                       -9      64 MiB       6      674 MiB   65 MiB


I think 65MIB  for decompressing is OK with current hardwares as long
as it saves good amount of space and bandwidth.


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