About docker's orchestra tool that can maximize utilization of server resources
Maximizing utilization is in general a NP-hard problem.
Mesos is a two step scheduler. Resources usage could be control by a framework. Mesos only present resources and it's on framework side to accept them or not. This means you can implement any algorithm to maximize utilization of cluster. What's more Mesos gives you oprtiunity to monitor slack resources and use them too with oversubscription.
In Kubernetes you also can plug your own scheduler. Kubernetes is one step scheduler but you can have multiple schedulers at once. See documentation for this: advanced scheduling in Kubernetes