I’m assuming you’re using Linux. This is from my ~/.bashrc
# parallel make
export NUMCPUS=`grep -c '^processor' /proc/cpuinfo`
alias pmake="time nice make -j$NUMCPUS --load-average=$NUMCPUS"
sample usage
samm@host src> echo $NUMCPUS
8
samm@host src> pmake
becomes time nice make -j8 --load-average=8.
To answer your specific question about putting this into a Makefile, I don’t find it practical to sprinkle this logic all over my Makefiles. Putting this into a top level Makefile also isn’t a great solution since I often build from sub-directories and wish to build them in parallel as well. However, if you have a fairly flat source hierarchy, it may work for you.