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Merge pull request #27891 from fromanirh/cpumanager-policy-options

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cpumanager: document cpu manager policy options
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Kubernetes Prow Robot
2021-07-22 05:15:51 -07:00
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parent f92e3ec2ba 2946586e77
commit be5f25eade
2 changed files with 20 additions and 1 deletions
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content/en/docs/tasks/administer-cluster/cpu-management-policies.md
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@@ -58,6 +58,9 @@ frequency is set through a new Kubelet configuration value
`--cpu-manager-reconcile-period`. If not specified, it defaults to the same
duration as `--node-status-update-frequency`.
The behavior of the static policy can be fine-tuned using the `--cpu-manager-policy-options` flag.
The flag takes a comma-separated list of `key=value` policy options.
### None policy
The `none` policy explicitly enables the existing default CPU
@@ -212,4 +215,14 @@ and `requests` are set equal to `limits` when not explicitly specified. And the
container's resource limit for the CPU resource is an integer greater than or
equal to one. The `nginx` container is granted 2 exclusive CPUs.
#### Static policy options
If the `full-pcpus-only` policy option is specified, the static policy will always allocate full physical cores.
You can enable this option by adding `full-pcups-only=true` to the CPUManager policy options.
By default, without this option, the static policy allocates CPUs using a topology-aware best-fit allocation.
On SMT enabled systems, the policy can allocate individual virtual cores, which correspond to hardware threads.
This can lead to different containers sharing the same physical cores; this behaviour in turn contributes
to the [noisy neighbours problem](https://en.wikipedia.org/wiki/Cloud_computing_issues#Performance_interference_and_noisy_neighbors).
With the option enabled, the pod will be admitted by the kubelet only if the CPU request of all its containers
can be fulfilled by allocating full physical cores.
If the pod does not pass the admission, it will be put in Failed state with the message `SMTAlignmentError`.