Now I update my openstack to queen,and use the nova-placement-api to provider resource.   I use "/resource_providers/{uuid}/inventories/MEMORY_MB" to update memory_mb allocation_ratio, then it success.But after some minutes,it recover to old value automatically. Then I find it report the value from compute_node in nova-compute automatically. But the allocation_ratio of compute_node was came from the nova.conf.So that means，We can't update the allocation_ratio until we update the nova.conf? But I wish to update the allocation_ratio dynamically other to update the nova.conf. I don't known how  to update resource allocation ratio dynamically.