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topologymanager: document topology manager policy options 

Signed-off-by: PiotrProkop <pprokop@nvidia.com>
pull/37668/head
PiotrProkop 2022-11-08 10:35:37 +01:00
parent e11d51afdc
commit 701ed987c5
2 changed files with 34 additions and 1 deletions
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12
content/en/docs/reference/command-line-tools-reference/feature-gates.md
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@ -196,6 +196,9 @@ For a reference to old feature gates that are removed, please refer to
| `TopologyAwareHints` | `true` | Beta | 1.24 | |
| `TopologyManager` | `false` | Alpha | 1.16 | 1.17 |
| `TopologyManager` | `true` | Beta | 1.18 | |
| `TopologyManagerPolicyAlphaOptions` | `false` | Alpha | 1.26 | |
| `TopologyManagerPolicyBetaOptions` | `false` | Beta | 1.26 | |
| `TopologyManagerPolicyOptions` | `false` | Alpha | 1.26 | |
| `UserNamespacesStatelessPodsSupport` | `false` | Alpha | 1.25 | |
| `VolumeCapacityPriority` | `false` | Alpha | 1.21 | - |
| `WinDSR` | `false` | Alpha | 1.14 | |
@ -727,6 +730,15 @@ Each feature gate is designed for enabling/disabling a specific feature:
- `TopologyManager`: Enable a mechanism to coordinate fine-grained hardware resource
assignments for different components in Kubernetes. See
[Control Topology Management Policies on a node](/docs/tasks/administer-cluster/topology-manager/).
- `TopologyManagerPolicyAlphaOptions`: Allow fine-tuning of topology manager policies,
experimental, Alpha-quality options.
This feature gate guards *a group* of topology manager options whose quality level is alpha.
This feature gate will never graduate to beta or stable.
- `TopologyManagerPolicyBetaOptions`: Allow fine-tuning of topology manager policies,
experimental, Beta-quality options.
This feature gate guards *a group* of topology manager options whose quality level is alpha.
This feature gate will never graduate to stable.
- `TopologyManagerPolicyOptions`: Allow fine-tuning of topology manager policies,
- `UserNamespacesStatelessPodsSupport`: Enable user namespace support for stateless Pods.
- `VolumeCapacityPriority`: Enable support for prioritizing nodes in different
topologies based on available PV capacity.

23
content/en/docs/tasks/administer-cluster/topology-manager.md
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@ -213,6 +213,28 @@ reschedule the pod. It is recommended to use a Deployment with replicas to trigg
the Pod.An external control loop could be also implemented to trigger a redeployment of pods
that have the `Topology Affinity` error.
### Topology manager policy options
Support for the Topology Manager policy options requires `TopologyManagerPolicyOptions`
[feature gate](/docs/reference/command-line-tools-reference/feature-gates/) to be enabled.
You can toggle groups of options on and off based upon their maturity level using the following feature gates:
* `TopologyManagerPolicyBetaOptions` default disabled. Enable to show beta-level options. Currently there are no beta-level options.
* `TopologyManagerPolicyAlphaOptions` default disabled. Enable to show alpha-level options. You will still have to enable each option using the `TopologyManagerPolicyOptions` kubelet option.
The following policy options exists:
* `prefer-closest-numa-nodes` (alpha, invisible by default, `TopologyManagerPolicyOptions` and `TopologyManagerPolicyAlphaOptions` feature gates have to be enabled)(1.26 or higher)
If the `prefer-closest-numa-nodes` policy option is specified, the `best-effort` and `restricted`
policies will favor sets of NUMA nodes with shorter distance between them when making admission decisions.
You can enable this option by adding `prefer-closest-numa-nodes=true` to the Topology Manager policy options.
By default, without this option, Topology Manager aligns resources on either a single NUMA node or
the minimum number of NUMA nodes (in cases where more than one NUMA node is required). However,
the `TopologyManager` is not aware of NUMA distances and does not take them into account when making admission decisions.
This limitation surfaces in multi-socket, as well as single-socket multi NUMA systems,
and can cause significant performance degradation in latency-critical execution and high-throughput applications if the
Topology Manager decides to align resources on non-adjacent NUMA nodes.
### Pod Interactions with Topology Manager Policies
Consider the containers in the following pod specs:
@ -330,4 +352,3 @@ assignments.
2. The scheduler is not topology-aware, so it is possible to be scheduled on a node and then fail
on the node due to the Topology Manager.