Re: Will 2021 be the year of build systems on gexps?

[Maxim Cournoyer <maxim.cournoyer@gmail.com>]

Hi Ludo!

Ludovic Courtès <ludo@gnu.org> writes:

> Hello!
>
> Ludovic Courtès <ludo@gnu.org> skribis:
>
>> Ludovic Courtès <ludo@gnu.org> skribis:
>>
>>> Over the last few days I’ve been head-down working on
>>> ‘wip-build-systems-gexp’, the mythical branch that brings gexps to build
>>> systems and packages, so we can say goodbye to
>>> ‘build-expression->derivation’.  And… it’s quite a ride!
>>
>> The current tip of ‘wip-build-systems-gexp’ Just Works; it’s being built,
>> it can build ‘guix’ and cross-build things like ‘sed’:
>>
>>   https://data.guix-patches.cbaines.net/repository/2/branch/wip-build-systems-gexp
>>
>>   https://ci.guix.gnu.org/jobset/wip-build-systems-gexp (though Cuirass
>>   currently has unrelated problems)
>
> It’s building and well!
>
>> In terms of performance, there’s still a ~10% slowdown when computing
>> derivations compared to the ‘core-updates’ revision the branch is based
>> on.
>
> I made some improvements yesterday (reducing object cache lookups and
> the number of entries therein), but we’re still in the 10% ballpark.
> WIP branch:
>
> $ git log |head -5
> commit 082df93be3472e0f38970634260af8c432420b35
> Author: Ludovic Courtès <ludo@gnu.org>
> Date:   Mon Mar 8 13:59:23 2021 +0100
>
>     gnu: docbook-xsl: Move 'use-modules' form to the top level.
> $ time GUIX_PROFILING=gc ./pre-inst-env guix build libreoffice --no-grafts -d
> /gnu/store/fsrbbi8vfrwwdz2dlyzpfvvnky03nczz-libreoffice-6.4.7.2.drv
> Garbage collection statistics:
>   heap size:        87.18 MiB
>   allocated:        254.25 MiB
>   GC times:         16
>   time spent in GC: 0.74 seconds (31% of user time)
>
> real	0m2.225s
> user	0m2.415s
> sys	0m0.087s
>
>
> Compared to ‘core-updates’:
>
> $ git log |head -5
> commit b35581bd63d929e83d18f42b067f63efc867353c
> Author: Efraim Flashner <efraim@flashner.co.il>
> Date:   Sun Mar 21 09:42:06 2021 +0200
>
>     gnu: openjpeg: Update to 2.4.0.
> $ time GUIX_PROFILING=gc ./pre-inst-env guix build libreoffice --no-grafts -d
> /gnu/store/irdhm6jx30bgdxvgb0an1mn223rzshkg-libreoffice-6.4.7.2.drv
> Garbage collection statistics:
>   heap size:        79.18 MiB
>   allocated:        216.51 MiB
>   GC times:         16
>   time spent in GC: 0.74 seconds (33% of user time)
>
> real	0m2.094s
> user	0m2.277s
> sys	0m0.106s

This looks reasonable!

>> Here’s what I’d like to do in the coming days, if that doesn’t interfere
>> with what others have in mind for the upcoming release:
>>
>>   • Monitor build failures due to typos/thinkos made while adjusting
>>     build systems;
>>
>>   • Merge on ‘core-updates’.
>
> I’ll go ahead with that if there are no objections.

Sounds good!  Thanks for picking up this work! :-)

Maxim