83 lines
2.3 KiB
Markdown
83 lines
2.3 KiB
Markdown
---
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reviewers:
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- derekwaynecarr
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title: Manage HugePages
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content_template: templates/task
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---
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{{% capture overview %}}
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{{< feature-state state="beta" >}}
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Kubernetes supports the allocation and consumption of pre-allocated huge pages
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by applications in a Pod as a **beta** feature. This page describes how users
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can consume huge pages and the current limitations.
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{{% /capture %}}
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{{% capture prerequisites %}}
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1. Kubernetes nodes must pre-allocate huge pages in order for the node to report
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its huge page capacity. A node may only pre-allocate huge pages for a single
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size.
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The nodes will automatically discover and report all huge page resources as a
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schedulable resource.
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{{% /capture %}}
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{{% capture steps %}}
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## API
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Huge pages can be consumed via container level resource requirements using the
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resource name `hugepages-<size>`, where size is the most compact binary notation
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using integer values supported on a particular node. For example, if a node
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supports 2048KiB page sizes, it will expose a schedulable resource
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`hugepages-2Mi`. Unlike CPU or memory, huge pages do not support overcommit.
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```yaml
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apiVersion: v1
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kind: Pod
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metadata:
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generateName: hugepages-volume-
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spec:
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containers:
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- image: fedora:latest
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command:
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- sleep
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- inf
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name: example
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volumeMounts:
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- mountPath: /hugepages
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name: hugepage
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resources:
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limits:
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hugepages-2Mi: 100Mi
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volumes:
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- name: hugepage
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emptyDir:
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medium: HugePages
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```
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- Huge page requests must equal the limits. This is the default if limits are
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specified, but requests are not.
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- Huge pages are isolated at a pod scope, container isolation is planned in a
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future iteration.
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- EmptyDir volumes backed by huge pages may not consume more huge page memory
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than the pod request.
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- Applications that consume huge pages via `shmget()` with `SHM_HUGETLB` must
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run with a supplemental group that matches `proc/sys/vm/hugetlb_shm_group`.
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- Huge page usage in a namespace is controllable via ResourceQuota similar
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to other compute resources like `cpu` or `memory` using the `hugepages-<size>`
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token.
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## Future
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- Support container isolation of huge pages in addition to pod isolation.
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- NUMA locality guarantees as a feature of quality of service.
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- LimitRange support.
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{{% /capture %}}
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