As far as I know the model in CloudSim does not take into account the memory footprint of the VM yet ( see https://www.researchgate.net/post/Which_simulator_would_be_the_best_for_live_migration_in_cloud_computing )
I invite you (and other researchers interested by VM scheduling policies) to give a look at the VMPlaceS project: http://beyondtheclouds.github.io/VMPlaceS/
VMPlaceS is a dedicated framework built on top of the Simgrid VM live migration capabilities to evaluate and compare VM placement algorithms.