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Re: [proposal] use xz compression for Debian package by default

On Tue, Aug 28, 2012 at 12:10:18PM +0900, Hideki Yamane wrote:
>  We know some packages are better to use gzip, but it's an exception. Using xz
>  is best choice for rest 99.99% of packages. We can deal with such exception
>  by specifying gzip for that (e.g. openclipart-png).

Or even no compression at all. But this needs to be checked.

>  *** what's the best compress option for default? ***
>   low CPU                : --check=crc32               -> -10% time

You tested this on a CPU without 64-Bit multiplication unit? Otherwise
it should not be visible.

>   low memory             : --lzma2=dict=64KiB (or -0)  -> use 100KiB mem

I think we could go for -2 or -3. You can't run Debian on anything with
less then 32MiB RAM.

>   use arch optimization? : Yes, if we can (*)          -> -10% size

No good idea. The doc clearly stats:

| [...] so it generally isn't good to blindly apply a BCJ filter when
| compressing binary packages for distribution.

>  *** how to find appropriate compression rate(1, 6 or 9) for xz? ***
>   build your package with each option :-)

This is not appropriate. Needing 700MiB to compress is no good idea.


Madness has no purpose.  Or reason.  But it may have a goal.
		-- Spock, "The Alternative Factor", stardate 3088.7

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