[FFmpeg-devel] [RFC] New build system

[James Almer]

On 6/18/2018 3:44 PM, Hendrik Leppkes wrote:
> 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.

Unless the same can be achieved without spawning a new bash process for
every single dep check, then there's not much we can do with shell to
improve the current situation.

So i agree moving onto something else, like a pure python 3 script,
might be a good idea. I'm not sure about Meson since it definitely will
be a pain on non standard systems, not to mention the PoC submitted
doesn't even work with a release currently actually available on any
package manager.