[OE-core] [PATCH] local.conf.sample: Add automatic defaults for BB_NUMBER_THREADS and PARALLEL_MAKE

[Enrico Scholz]

Koen Kooi <koen-QLwJDigV5abLmq1fohREcCpxlwaOVQ5f at public.gmane.org>
writes:

>> +# Default to setting automatically based on cpu count
>> +BB_NUMBER_THREADS ?= "${@oe.utils.cpu_count()}"
>
> I've noticed that after 4 threads IO becomes a big bottleneck when you
> have things like webkit, qt, asio etc in the buildqueue. Combine that
> with issues like every make -j thread taking >2GB ram with asio and
> webkit this default seems a bit high. I'd use 0.5*numcpu with a lower
> bound of 2.

limitting the load mitigates this (high i/o increases it); e.g.

PARALLEL_MAKE = "\
  ...
  -l ${@int(os.sysconf(os.sysconf_names['SC_NPROCESSORS_ONLN'])) * 150/100} \
"

Enrico