weighing compute nodes by real memory available when filtering

Hello Experts, I would like to ask if there is an available implementation to achieve filtering or weighing compute nodes by the real memory usage. From my observation, nova filters the compute-nodes by computing the summation of all instances' flavor ram and reserved ram. But since reserved ram is only an empirical value, sometimes compute nodes could potentially use more ram. Making things even worse is the ram allocation ratio could be more than 1. So I would like to know if there is an available implementation such that when the real memory available (from procfs) is low, the compute-node could be given a smaller weight or simply filtered out. Thank you. -- Best Regards, Jiatong Shen