OK but what was the utilization? I'm not really sure K8s is state-of-the-art either. There are published research papers about very-large-scale clusters with 80%+ resource utilization.
In our production experience, utilization had far more to do with the service owners (or autoscalers/auto-tuners) correctly choosing the cgroups and CPU scheduler allocations, as well as the kernel settings for cgroup slicing and CPU scheduler. We had Mesos clusters with 3% utilization and have Kubernetes clusters with 95%+ utilization. But we also have Kubernetes clusters with <10% utilization.
To be fair, Kubernetes right now only schedules relatively small clusters. But it turns out that the majority of the world is not Facebook or Google and only needs relatively small clusters.
Unfortunately the original article is lost, but here's a summary: https://daringfireball.net/linked/2015/04/29/siri-apache-mes...