double queryFraction() {
            OptionalDouble writeRate = clusterTimeseries().writeRate(scalingDuration(), at);
            if (averageQueryRate(at).orElse(0) == 0 && writeRate.orElse(0) == 0) return queryFraction(0.5);
            return queryFraction(averageQueryRate(at).orElse(0) / (averageQueryRate(at).orElse(0) + writeRate.orElse(0)));
        }
The estimated fraction of cpu usage which goes to processing queries vs. writes
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/autoscale/ClusterModel.java