Re: llvm on aarch64 builds very slowly

[Ricardo Wurmus]

Ricardo Wurmus <rekado@elephly.net> writes:

> Hi Guix,
>
> I had to manually run the build of llvm 11 on aarch64, because it would
> keep timing out:
>
>     time guix build 
> /gnu/store/0hc7inxqcczb8mq2wcwrcw0vd3i2agkv-llvm-11.0.0.drv --timeout=999999 
> --max-silent-time=999999
>
> After more than two days it finally built.  This seems a little
> excessive.  Towards the end of the build I saw a 1% point progress
> increase for every hour that passed.
>
> Is there something wrong with the build nodes, are we building llvm 11
> wrong, or is this just the way it is on aarch64 systems?

I now see that gfortran 10 also takes a very long time to build.  It’s
on kreuzberg (10.0.0.9) and I see that out of the 16 cores only *one* is
really busy.  Other cores sometimes come in with a tiny bit of work, but
you might miss it if you blink.

Guix ran “make -j 16” at the top level, but the other make processes
that have been spawned as children do not have “-j 16”.  There are
probably 16 or so invocations of cc1plus, but only CPU0 seems to be busy
at 100% while the others are at 0.

What’s up with that?

-- 
Ricardo