Massimo- > To decide if an instance should go to a compute node with or without > overcommitment is easy; e.g. it could be done with host aggregates + > setting metadata to the relevant flavors/images. You could also use custom traits. > But is it in some way possible to decide that a certain project has a > quota of x VCPUs without overcommitment, and y VCPUs with overcommitments ? I'm not sure whether this helps, but it's easy to detect the allocation ratio of a compute node's VCPU resource via placement with GET /resource_providers/$cn_uuid/inventories/VCPU [1]. But breaking down a VCPU quota into different "classes" of VCPU sounds... impossible to me. But since you said > In particular I would like to use some compute nodes without > overcommitments ...perhaps it would help you to use PCPUs instead of VCPUs for these. We started reporting PCPUs in Train [2]. efried [1] https://docs.openstack.org/api-ref/placement/?expanded=show-resource-provider-inventory-detail#show-resource-provider-inventory [2] http://specs.openstack.org/openstack/nova-specs/specs/train/approved/cpu-resources.html