How to increase maximum user cpu usage allowed on a multi core system?

[Heinz Diehl]

On 09.03.2015, Martin Cigorraga wrote: 

> Just a minor clarification: when compiling, the -j flag should point to a
> unit above your available cores in order to fully utilize all of them.

Curious what would happen, I remembered this mail when compiling a new kernel
today. A "nice -n 19 make -j" opened *hundreds* of cc incarnations, pushed the
load to over 800 and seriously blocked the machine (an 8-core Xeon with 16 GB
of RAM) within *seconds*!