1. An apparatus comprising a computer processor, a computer memory operatively coupled to the computer processor, the computer memory having disposed within it computer program instructions that, when executed by the computer processor, cause the apparatus to perform operations comprising: administering a plurality of virtual machines (‘VMs’) in a distributed computing environment, the distributed computing environment comprising a plurality of hosts, one or more of the hosts executing a virtual machine monitor (‘VMM’), each VMM supporting execution of one or more VMs; assigning, by a VMM manager, the VMMs of the distributed computing environment to a logical tree topology, including assigning one of the VMMs as a root VMM of the tree topology; and executing, amongst the VMMs of the tree topology, an allgather operation, including: sending, by the root VMM, to a plurality of other VMMs in the tree topology, a request to retrieve VMs supported by the plurality of other VMMs; pausing, by each of the plurality of other VMMs, a VM supported by the VMM; providing, by each of the plurality of other VMMs as a response to the root VMM's request, each paused VM supported by the plurality of other VMMs; and broadcasting, by the root VMM, a same set of the received VMs to each of the plurality of other VMMs.