1. A method comprising: at a network management appliance that is in communication with network resources and computing resources used by a plurality of virtual machines executed by the computing resources for providing one or more services, collecting usage metrics from network components of the network resources operating with respect to traffic that passes through the network resources as a result of the plurality of virtual machines executed by the computing resources; and computing a virtual machine workload cost from the usage metrics at a core access switch level of the network resources based on the usage metrics collected for the network traffic passing through the network components of the network resources.