public DynamicThrottlePolicy setEfficiencyThreshold(double efficiencyThreshold) {
        this.efficiencyThreshold = efficiencyThreshold;
        return this;
    }
Determines where on each latency level the attractor sits. 2 is at the very end, and makes this go *boom*.
0.2 is at the very start, and makes the algorithm more conservative. Probably fine to stay away from this.
messagebus/src/main/java/com/yahoo/messagebus/DynamicThrottlePolicy.java