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Re: [patch] build xz (instead of bz2) compressed tarballs and diffs
On 15.05.2017 12:04, Markus Trippelsdorf wrote:
> On 2017.05.15 at 16:24 +0200, Jakub Jelinek wrote:
>> On Mon, May 15, 2017 at 04:13:44PM +0200, Markus Trippelsdorf wrote:
>>> On 2017.05.15 at 14:02 +0000, Joseph Myers wrote:
>>>> The xz manpage warns against blindly using -9 (for which --best is a
>>>> deprecated alias) because of the implications for memory requirements for
>>>> decompressing. If there's a reason it's considered appropriate here, I
>>>> think it needs an explanatory comment.
>>>
>>> I think it is unacceptable, because it would increase memory usage when
>>> decompressing over 20x compared to bz2 (and over 100x while compressing).
>>
>> The memory using during compressing isn't that interesting as long as it
>> isn't prohibitive for sourceware or the machines RMs use.
>> For the decompression, I guess it matters what is actually the memory needed
>> for decompression the -9 gcc tarball, and compare that to minimal memory
>> requirements to compile (not bootstrap) the compiler using typical system
>> compilers. If compilation of gcc takes more memory than the decompression,
>> then it should be fine, why would anyone try to decompress gcc not to build
>> it afterwards?
>
> Ok, it doesn't really matter. With gcc-7.1 tarball:
>
> size: 533084160 (uncompressed)
>
> -9:
> xz -d gcc.tar.xz
> 4.71user 0.26system 0:04.97elapsed 100%CPU (0avgtext+0avgdata 67804maxresident)k
> size: 60806928
>
> -6 (default):
> xz -d gcc.tar.xz
> 4.88user 0.28system 0:05.17elapsed 99%CPU (0avgtext+0avgdata 10324maxresident)k
> size: 65059664
>
> So -9 is actually just fine.
ok, updated the script to use xz --best by default. trunk and the gcc-7-branch.
Matthias