Service provider management of virtual instances corresponding to hardware resources managed by other service providers

A dynamic pool of virtual instances is managed. Each virtual instance corresponds to one or more hardware resources. Management includes tracking for each virtual instance: historical and current utilization, an operating cost, a capacity, and a characteristic associated with a capability of the hardware resources to which the virtual instance corresponds. A given virtual instance of the dynamic pool of virtual instances on which to schedule a workload for completion is selected, based on a characteristic of the workload matching the characteristic of the given virtual instance, and taking into account the capacity, the current utilization, and the operating cost of the given virtual instance. The hardware resources are managed by service providers different than a service provider managing computing devices on which the virtual instances are managed and the workload is scheduled, and the workload is received from a customer different than any of these service providers.