[libvirt] [RFC PATCH] build: increase xz compression level

[Daniel P. Berrange]

On Fri, Jun 24, 2016 at 12:34:57AM +0200, Ján Tomko wrote:
> Increase the default compression level to 9 from 6.
> 
> This also increases decompression memory requirements
> from 9 MB to 65 MB.

ok, that's still tiny compared to memory used by gcc to actually
compile libvirt

> ---
> The resulting tarball is 880 kB smaller [10.5 MB]
> Level 8 requires 33 MB and saves 520 kB [10.8 MB]
> Level 7 requires 17 MB and saves 170 kB [11.2 MB]
> Compression time is not much different since we're already using --extreme.

That's ok then.

> 
> The Linux kernel also uses -9, but the tarball is 8x our size.
> 
>  cfg.mk | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/cfg.mk b/cfg.mk
> index e93114c..ebafb0f 100644
> --- a/cfg.mk
> +++ b/cfg.mk
> @@ -16,6 +16,9 @@
>  # along with this program.  If not, see
>  # <http://www.gnu.org/licenses/>.
>  
> +XZ_OPT ?= -9e
> +export XZ_OPT

The cfg.mk is for controlling gnulib syntax-check code. This
should be part of Makefile.am


Regards,
Daniel
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