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Some Tips and Tricks

Speed up recompilation with ccache

Some images (eg the SL7 kitchen sink image) have ccache installed. This can speed up rebuild times by about a factor of 10. Especially good if the cache is put on a fast SSD.

To use it I place into my ~/.wcdo/project-local.rc file:

bv-ccache-me () {
    if [ ! -d /ccache ] ; then
        echo "No ccache directory, not caching."
        return
    fi
    if [ ! -d /ccache/bin ] ; then
        mkdir /ccache/bin
        for n in gcc g++ cc c++ cpp ; do
            ln -s /bin/ccache /ccache/bin/$n
        done
    fi
    if [ ! -d /ccache/cachedir ] ; then
        mkdir /ccache/cachedir
    fi
    export CCACHE_DIR=/ccache/cachedir

    export CC=/ccache/bin/cc
    export CXX=/ccache/bin/c++
    export CPP=/ccache/bin/cpp
    path-prepend /ccache/bin 

}
bv-unccache-me () {
    unset CC
    unset CXX
    unset CPP
    path-remove /ccache/bin
}

To gain access to my SSD on /ccache in the container I add to my ~/.wcdo/project-local.sh this bit:

if [ -d "/data/fast/bviren/ccache" ] ; then
    wcdo_bindings="$wcdo_bindings /data/fast/bviren/ccache:/ccache"
fi

Then, inside a container I do:

$ bv-ccache-me

And configure/build as usual. Note, the first build with ccache may be slower but subsequent rebuilds, even after a “clean” will be much faster. For building WCT on 2x Xeon CPU E5-2630 v4 @ 2.20GHz here are some representative times for a clean build:

$ ./wct clean
$ ./wct -p --notests

native	first ccache	subsequent
44 s	55 s	6.4 s