double fixedFraction() {
            if (clusterSpec().type().isContainer()) return 1.0;
            double fixedMemory = nodeMemoryOverheadGb +
                                 (averageReal() - nodeMemoryOverheadGb) * 0.05; // TODO: Measure actual content node usage
            return fixedMemory / averageReal();
        }
Returns the fraction of memory of the current allocation which is currently consumed by
fixed data structures which take the same amount of space regardless of document volume.
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/autoscale/ClusterModel.java