You might be interested in this thread [1] where I described an idea for how to incorporate the latency penalty into the eviction decision. A developer even hacked a prototype that showed promise. The problem is that there is not enough variety in the available trace data to be confident that a design isn't overly fit to a particular workload and doesn't generalize. As more data sets become available it will become possible to experiment with ideas and fix unexpected issues until a correct, simple, elegant design emerges.