Kubernetes Node Allocatable 表示整个集群当前节点pod可用的计算资源量，该配置可以保证调度器不会超额申请计算资源，目前支持CPU,memory,storage这几个参数。

      Node Capacity
---------------------------
|     kube-reserved       |
|-------------------------|
|     system-reserved     |
|-------------------------|
|    eviction-threshold   |
|-------------------------|
|                         |
|      allocatable        |
|   (available for pods)  |
|                         |
|                         |
---------------------------

https://k8smeetup.github.io/docs/tasks/administer-cluster/out-of-resource/#eviction-policy https://yq.aliyun.com/articles/604524 https://github.com/rootsongjc/qa/issues/3 https://kubernetes.io/docs/tasks/administer-cluster/reserve-compute-resources/#general-guidelines https://kubernetes.io/docs/tasks/administer-cluster/reserve-compute-resources/ https://github.com/kubernetes/community/blob/master/contributors/design-proposals/node/node-allocatable.md#recommended-cgroups-setup https://github.com/rancher/rancher/issues/17177 https://github.com/kubernetes/kubernetes/blob/v1.11.6/pkg/kubelet/cm/cgroup_manager_linux.go#L259 http://www.kbase101.com/question/18764.html https://access.redhat.com/documentation/zh-cn/red_hat_enterprise_linux/7/html/resource_management_guide/chap-using_control_groups#sec-Creating_Cgroups https://k8smeetup.github.io/docs/tasks/administer-cluster/reserve-compute-resources/ https://godoc.org/k8s.io/kubernetes/pkg/kubelet/apis/config#KubeletConfiguration