Parallelized Make

Since the introduction of dual core machines the number of mono core machines is declined and almost no computer of that kind are sold at all. Having such a machine is clearly a big advantage, but for many things you must tell programs that you are on a multi-cpu machines to make them use all the power. So i wrote a very little and simple script to replace the default make.

Just place this script in a path before the standard make. I made a folder ~/.bin in my home directory and modified the PATH accordingly export PATH=~/.bin:$PATH

#!/bin/sh

# verbosity check
if [ "$VERBOSE" = "yes" ] ; then
	verbose=yes
fi

# Get the number of cores
if [ -z $NCPU ] ; then
    tmp=$(sysctl hw.ncpu)
    NCPU=${tmp#hw.ncpu: }
	if [ "$VERBOSE" = "yes" ] ; then
		echo "Parallelization enabled with $NCPU threads"
	fi
fi

j=$(($NCPU*5/2))
if [ ! -z $NOPMAKE ] ; then
    echo "Parallelization Disabled" >&2
    /usr/bin/make $@
    exit $?
fi

# Start the compilation in parallel
if [ ! -z "$DISTCC_HOSTS" ] ; then
    if [ -z "$HOST_COUNT" ] ; then
        export HOST_COUNT=$(echo $DISTCC_HOSTS | wc -w)
    fi
    /usr/bin/make CC='distcc /usr/bin/gcc' CXX='distcc /usr/bin/g++' -j$((j+$HOST_COUNT)) $@
else
    /usr/bin/make -j$j $@
fi

To make it work on linux the sysctl command must be replaced with a count of the lines containing “processor” in the file /proc/cpuinfo. Something like grep processor /proc/cpuinfo | wc -l