[arch-general] MAKEFLAGS and dragon.archlinux.org

[Archange]

Le 31/03/2021 à 15:25, u34--- via arch-general a écrit :
> I think there are no real machines with 5 cores, or 5 cpus. If
> dragon.archlinux.org actually has 5 cpus then do skip this message.

Actually this box does not exist anymore, but IIRC it had 32 cores.

> Refering to https://wiki.archlinux.org/index.php/DeveloperWiki:PKGBUILD.com :
> It states it describes the build server at dragon.archlinux.org. At
> https://wiki.archlinux.org/index.php/DeveloperWiki:PKGBUILD.com#Packager_&&_Makeflags
> it suggests to use
>
>      MAKEFLAGS=-j5
>
> https://wiki.archlinux.org/index.php/Makepkg#Parallel_compilation
> suggets to use the number of cores here.
> I don't know what the implications of using a wrong number in MAKEFLAGS.
> Or even if there are any implications at all. Still, why not state the
> correct number, or use $(nproc)?

Implications are only on build time. Generally it’s a good idea to use 
nproc+1 to avoid waiting threads, but using a lower value could be for 
ressources sharing. We are numerous users on the build machine, so not 
using all the ressources for very big projects is a good idea (even if 
they are very few of them that would block the machine for a long time). 
Also, they are not many projects than can leverage the 64 threads available.

But I actually built ParaView using -j65, and it was amazing to have it 
built in ~10 min.

Regards,
Archange