'memory_usage': {
        'options': [None, 'Memory Usage', 'MiB', 'memory usage', 'varnish.memory_usage', 'stacked'],
        'lines': [
            ['memory_free', 'free', 'absolute', 1, 1 << 20],
            ['memory_allocated', 'allocated', 'absolute', 1, 1 << 20]]