[OE-core] [PATCH] Set XZ_COMPRESSION_LEVEL to -9

[Adrian Bunk]

On Fri, Apr 12, 2019 at 04:12:19PM -0700, Khem Raj wrote:
> On Fri, Apr 12, 2019 at 2:09 PM Adrian Bunk <bunk at stusta.de> wrote:
> >
> > It is consistent with other compressors also using their
> > best compression.
> >
> > xz is currently the option that offers best compression,
> > using settings even lower than the default is surprising
> > and makes it harder to choose the best available compression.
> >
> > For anyone who cares about compression time using a different
> > option like gzip or bzip2 is the logical choice.
> >
> > For decompression, better compressed is actually faster
> > to decompress.
> 
> I worry about resources we need to spend when creating these archives.
> Can you post some comparisons
> along to assess the performance.

On my laptop single-threaded compression of an image I am frequently
building takes 20s with -3 and 55s with -9.

Building the whole image from scratch takes more than 2 hours.

If you care about resources spent, I remember it saved me around 10 
minutes build time when I changed OPKGBUILDCMD from the default "xz -6" 
to "gzip -1" - for the common case where package feeds are not used 
there is no point in spending time on compression and decompression.

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed