第 2 章 Recommended host practices
This topic provides recommended host practices for OpenShift Container Platform.
2.1. Recommended node host practices
The OpenShift Container Platform node configuration file contains important options. For example, two parameters control the maximum number of pods that can be scheduled to a node: podsPerCore and maxPods.
When both options are in use, the lower of the two values limits the number of pods on a node. Exceeding these values can result in:
- Increased CPU utilization.
- Slow pod scheduling.
- Potential out-of-memory scenarios, depending on the amount of memory in the node.
- Exhausting the pool of IP addresses.
- Resource overcommitting, leading to poor user application performance.
In Kubernetes, a pod that is holding a single container actually uses two containers. The second container is used to set up networking prior to the actual container starting. Therefore, a system running 10 pods will actually have 20 containers running.
podsPerCore sets the number of pods the node can run based on the number of processor cores on the node. For example, if podsPerCore is set to 10 on a node with 4 processor cores, the maximum number of pods allowed on the node will be 40.
kubeletConfig: podsPerCore: 10
Setting podsPerCore to 0 disables this limit. The default is 0. podsPerCore cannot exceed maxPods.
maxPods sets the number of pods the node can run to a fixed value, regardless of the properties of the node.
kubeletConfig:
maxPods: 250