[FFmpeg-devel] [RFC] New build system

[Hendrik Leppkes]

On Mon, Jun 18, 2018 at 8:19 PM Michael Niedermayer
<michael at niedermayer.cc> wrote:
>
> On Mon, Jun 18, 2018 at 06:52:18PM +0200, Nicolas George wrote:
> > Tomas Härdin (2018-06-18):
> > > Others have mentioned this already, but it bears repeating: the build
> > > (make) isn't what's so slow, configure is. I went ahead and did some
> > > profiling on it based on the StackOverflow thread that pops up when one
> > > Web-searches "bash profiling" [1]. I went with what the second guy in
> > > there says, because the first method eventually invokes the OOM killer.
> >
> > Before that, I suspect it would have been interesting to test a
> > configure from two years ago, and bissecting if it happens to be much
> > faster.
>
> The speed of configure declined very significantly over time, here are some
> quick tests, not full bisects:
>
> but theres another point which i have not seen anyone make but maybe i missed
> it.
> If changes which decrease speed go in unhindered and without correction then no
> system, not a custom one, no meson no autotools, no cmake is guranteed to
> prevent such speed decline.
> Of course some of the decline will be due to added features and the added tests
> they need.
>

The biggest recent slowdown is undoubtly from the change to how
depdencies are resolved, but the result of the change is also a much
better outcome in selected link libraries and generated pkg-config
files (only those appropriate for a specified library, instead of all
of them).
Of course one could try to investigate to implement the same thing
differently, but shell is really getting at its limit there.

- Hendrik