Re: [PATCH 2/3] kbuild: handle module compression while running 'make modules_install'.

Bertrand Jacquin
2014-08-19T18:54:11Z

Hi,

D'ar meurzh 19 a viz Eost 2014 e 19 eur 55, « Rusty Russell » he deus skrivet :
> Andi Kleen <andi@firstfloor.org> writes:
> > Bertrand Jacquin <beber@meleeweb.net> writes:
> >>
> >> +# CONFIG_MODULE_COMPRESS, if defined, will cause module to be compressed
> >> +# after they are installed in agreement with CONFIG_MODULE_COMPRESS_GZIP
> >> +# or CONFIG_MODULE_COMPRESS_XZ.
> >> +
> >> +mod_compress_cmd = true
> >> +ifdef CONFIG_MODULE_COMPRESS
> >> + ifdef CONFIG_MODULE_COMPRESS_GZIP
> >> + mod_compress_cmd = gzip -n -9
> >
> > Please don't use gzip -9. The gain is very small, but it can make
> > the time to compress much longer. Just use plain gzip.
>
> Interesting:
>
> $ time find * -name '*.ko' | xargs -n 1 gzip
> real 0m9.404s
> user 0m7.283s
> sys 0m1.667s
> $ du -c `find * -name '*.ko.gz'` | tail -n1
> 56412 total
>
> time find * -name '*.ko' | xargs -n 1 gzip -9
> real 1m1.968s
> user 0m58.850s
> sys 0m1.786s
> $ du -c `find * -name '*.ko.gz'` | tail -n1
> 55764 total
>
> $ time find * -name '*.ko' | xargs -n 1 xz
> real 1m23.396s
> user 1m13.893s
> sys 0m9.134s
> $ du -c `find * -name '*.ko.xz` | tail -n1
> 46868 total
>
> $ time find * -name '*.ko' | xargs -n 1 xz -9
> real 1m47.202s
> user 1m25.962s
> sys 0m21.298s
> $ du -c `find * -name '*.ko.xz` | tail -n1
> 46868 total
>
> So, Andi is right. Please skip -9 for both options: it makes little
> (.gz) or no (.xz) difference and it slows things down.

Thank you Andi and Rusty for the feedback. I'm current updating patches
to drop -9 usage.

--
Beber