title: how to call optimizeAllocation to migrate vms in cloudsim
body: <p>i m working on cloudsim to implement an genetic algorithm to find the optimal placement of vms in hosts.
  in the begening i need to put vms randomly ( i created a class that extends from <strong>VmAllocationPolicy</strong> )
  then i need to optimize vm allocation by migrating them to other hosts : i rode that i have to implement optimizeAllocation method inside my policy , i did it but i don't know how to execute it (optimizeAllocation) </p>