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Re: Something like nocompress DEB_BUILD_OPTION

On 20 November 2012 23:21, Guillem Jover <guillem@debian.org> wrote:
> On Sat, 2012-11-10 at 13:52:22 +0100, Bastian Blank wrote:
>> On Fri, Nov 09, 2012 at 07:48:22PM +0100, Guillem Jover wrote:
>> Okay. I did some tests with various packages. From binary only to text
>> only.
> Thanks for the tests Bastian. It would still be nice to see a bigger
> sample, if the tests only consisted of these 4 packages, though.
>> Package                   | gzip -6  | gzip -9  | gzip | xz -1
>> --------------------------+----------+-----------------+---------
>> libc6                     |  4339010 |  4321933 | 0.5% |  2938132
>> perl-modules              |  3874170 |  3822719 | 1.5% |  3248392
>> gnome-user-guide          |  9217494 |  9172395 | 0.5% |  7589076
>> linux-image-3.2.0-4-amd64 | 32928159 | 32522228 |      | 25945856
>> "gzip -9" is always much slower then "gzip -6". It is at most 2% better.
>> "xz -1" is usualy faster then "gzip -9" and much better. However most
>> packages only needs seconds to compress, so the difference will no
>> really matter.
>> So instead of switching to gzip -6, a switch to xz -1 would make more
>> sense in term of size and also speed.
>> So my proposal would be:
>> - Don't do anything for Wheezy.
>>   Any change may break the CD creation.
>> - Switch to xz per default for Jessie.
>>   xz -3 is often faster in compressing stuff then gzip -9. -6 needs a
>>   lot of memory, especially for compressing the files, so reducing the
>>   default to -3 may make sense and does not cost much.
> I've already mentioned in some other thread that for dpkg 1.17.x (that
> is after wheezy), I'll be switching dpkg-deb to xz as the default
> compressor, as that seemed the consensus; but that does not mean that
> if the default compression level for gzip is suboptimal (as it seems
> it is), that cannot be changed too.
> For changing xz default compression level I'd like to see the
> implications on a wider dataset, also we should take into account that
> compression is only done once, so I don't think that's such an issue,
> if the time and memory are not really onerous.

While I appreciate the discussions around default compression
algorithms and their setting, I'd rather this thread to stay on-topic.

Does the idea of providing a standard interface to disable compression
make sense? In the approximately similar fashion that noopt and
nostrip are justified?

This should be a standard interface via DEB_BUILD_OPTIONS, because
dh_builddeb / dpkg-deb is not the only way to build compliant binary

Please continue discussing default compression options, but please use
another thread/topic.

Just as I do now, I will continue to want the nocompress option
regardless of current or future default/non-default compression
algorithms and options. I'd like to gather consensus on how (in)sane
this idea is though before submit a patch for debian policy.



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