148422597X Kubernetes Management Design Patterns [Vohra 2017-01-29] {E559F6BB}

Chapter 10 ■ Configuring Compute Resources
Overcommitting Resource Limits
As shown in an earlier example, a maximum of three pods can be scheduled on a node with the allocated
requests consuming 90% of allocable CPU. The memory limits are at 300%, which makes the limits
overcommitted. If all the pods were to request their maximum allocable memory concurrently, the resource
consumption would exceed 100% and some pods would terminate. Even with a single pod on a node the
memory limits are overcommitted at 109%, though not by much, as shown in Figure 10-22.
Figure 10-22. Overcommitted memory limits
Reserving Node Resources
Pods are not the only objects or processes consuming resources on a node. It may be suitable to reserve
some resources for non-pod processes such as system processes. Resources may be reserved by running a
placeholder pod. Create a pod definition file pod-reserve-resource.yaml. Run the Docker image gcr.io/
google_containers/pause and specify resource limits for resources to be reserved such as 200m for cpu and
200Mi for memory.
apiVersion: v1
kind: Pod
metadata:
name: reserve-resource
spec:
containers:
- name: reserve-resource
image: gcr.io/google_containers/pause:0.8.0
resources:
limits:
cpu: “0.1”
memory: 200Mi
The pod definition file is shown in a vi editor in Figure 10-23.
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