[libvirt] [PATCH v2] maint: Switch to xz compressed PAX release archives

[Ján Tomko]

On Wed, Jun 15, 2016 at 10:31:16AM -0400, Laine Stump wrote:
>On 06/15/2016 09:03 AM, Andrea Bolognani wrote:
>> This allows us to produce releases that are roughly a third in
>> size, have no limitation on path length, and are still readable
>> by all supported platforms.
>> ---
>
>I just want to point out that the tarfile is built every time you run
>"make rpm" (which I do quite a lot - I prefer installing rpms to the
>carnage created by make install), and this increases the time for make
>rpm on my system by 1min38sec. (jtomko may have something to say about
>that, since he's been interested in shaving fractions of a second off
>the build time in the last few days :-O)
>

Use:
XZ_OPT="-3 --threads=0" make rpm

The most important speedup comes from dropping the '-e' option
which automake uses by default.

(-1 is faster than -0 in my testing, -2 and -3 take a few seconds more
 but drop megabytes off the size. All of them are faster and result in
 a smaller size than gz --best we used before)

On my RHEL, rpmbuild does not recompress sources by default,
so this will leave you with a larger srpm.
For binary data, the default level is 2:
%_binary_payload w2.xzdio
but even then the *rpms made with lower compression leves were
marginally larger than the default ones. I did not find out why.

Jan