On Thu, 15 Aug 2024 at 12:18, Monsees, Steven C (US) via
lists.yoctoproject.org
<steven.monsees=baesystems...@lists.yoctoproject.org> wrote:
>
>
> So, to be clear, in this example:
>
> There are 12 cores total on a board ...
> BB_NUMBER_THREADS="8", this tells bitbake to generate 8 tasks
>
> And, these tells do_make/do_install to each generate 2 tasks:
>
> PARALLEL_MAKE="-j 2"
> PARALLEL_MAKEINST="-j 2”
>
> All 12 cores are available to be used yocto build.
>
> Correct ?

No. This merely instructs bitbake to start a maximum of 8 tasks (it
can run less if the task dependency graph doesn't allow for more until
some task on the critical path completes and 'unlocks' further tasks),
and each of those tasks, if it's a make-driven one, will run on a
maximum of two cores. So you can end up anywhere from 8*2=16 processes
to just one process, and on average you're likely to under-utilize the
CPU with these settings, and have your build take longer than it could
be.

Please do stick with the defaults, they are picked to maximize CPU
utilization at small risk of running out of RAM.

Alex
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