In addition, we want pages to spread out evenly over these 3 generations, meaning an average 1/3 of total pages for each generation, which gives another reasonable range [1/2, 1/4]. Since the eviction reduces the number of old pages, we only need to check against the lower bound, i.e., 1/4. On the other hand, page (re)faults increase the number of young pages, so in this case, we need to check against the upper bound. I'll include these details in the next spin.
