Re: [gentoo-dev] [PATCH] check-reqs.eclass: clamp MAKEOPTS for memory/RAM usage

[Ulrich Mueller]

>>>>> On Tue, 04 Jan 2022, Sam James wrote:

> Crank down MAKEOPTS jobs if MAKEOPTS="-jN" is too high for the
> amount of RAM available (uses amount declared as needed
> in the ebuild). Typically should be ~2GB per job.

Where does this number 2 GB come from? The amount of RAM strongly
depends on the programming language and other factors, so I don't
believe that there's one number that can be used for everything.
(If only considering C and C++ 2 GB seems to be excessive, i.e. it
will limit parallel build more than necessary. When linking, the number
may be _much_ larger.)

Also not sure if I understand the arithmetic. Shouldn't it use
CHECKREQS_MEMORY as the basis of the calculation?

> +# @ECLASS-VARIABLE: CHECKREQS_MEMORY_MANGLE_JOBS
> +# @USER_VARIABLE
> +# @DESCRIPTION:
> +# Allow packages to reduce the number of multiprocessing (e.g. make, ninja) jobs
> +# to lower memory usage.
> +: ${CHECKREQS_MEMORY_MANGLE_JOBS=yes}

If anything, the feature should be opt-in rather than opt-out.

Ulrich