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Update hugepages documentation (#19008)

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* Update hugepages documentation

- described support for multiple huge page sizes
- described container isolation of the huge pages

* Add HugePageStorageMediumSize description

* update description for container isolation of hugepages

Signed-off-by: Byonggon Chun <bg.chun@samsung.com>

Co-authored-by: Byonggon Chun <bg.chun@samsung.com>
This commit is contained in:
Kubernetes Prow Robot
2020-03-05 09:44:38 -08:00
committed by GitHub
parent bd99f2ab93
commit 95a6e055d8
2 changed files with 58 additions and 13 deletions
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content/en/docs/reference/command-line-tools-reference/feature-gates.md
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@@ -103,6 +103,7 @@ different Kubernetes components.
| `ExperimentalHostUserNamespaceDefaulting` | `false` | Beta | 1.5 | |
| `EvenPodsSpread` | `false` | Alpha | 1.16 | |
| `HPAScaleToZero` | `false` | Alpha | 1.16 | |
| `HugePageStorageMediumSize` | `false` | Alpha | 1.18 | |
| `HyperVContainer` | `false` | Alpha | 1.10 | |
| `KubeletPodResources` | `false` | Alpha | 1.13 | 1.14 |
| `KubeletPodResources` | `true` | Beta | 1.15 | |
@@ -395,6 +396,7 @@ Each feature gate is designed for enabling/disabling a specific feature:
See [Enabling Endpoint Slices](/docs/tasks/administer-cluster/enabling-endpointslices/).
- `GCERegionalPersistentDisk`: Enable the regional PD feature on GCE.
- `HugePages`: Enable the allocation and consumption of pre-allocated [huge pages](/docs/tasks/manage-hugepages/scheduling-hugepages/).
- `HugePageStorageMediumSize`: Enable support for multiple sizes pre-allocated [huge pages](/docs/tasks/manage-hugepages/scheduling-hugepages/).
- `HyperVContainer`: Enable [Hyper-V isolation](https://docs.microsoft.com/en-us/virtualization/windowscontainers/manage-containers/hyperv-container) for Windows containers.
- `HPAScaleToZero`: Enables setting `minReplicas` to 0 for `HorizontalPodAutoscaler` resources when using custom or external metrics.
- `KubeletConfigFile`: Enable loading kubelet configuration from a file specified using a config file.
content/en/docs/tasks/manage-hugepages/scheduling-hugepages.md
+56 -13
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@@ -17,11 +17,11 @@ can consume huge pages and the current limitations.
{{% capture prerequisites %}}
1. Kubernetes nodes must pre-allocate huge pages in order for the node to report
its huge page capacity. A node may only pre-allocate huge pages for a single
size.
its huge page capacity. A node can pre-allocate huge pages for multiple
sizes.
The nodes will automatically discover and report all huge page resources as a
schedulable resource.
The nodes will automatically discover and report all huge page resources as
schedulable resources.
{{% /capture %}}
@@ -30,12 +30,51 @@ schedulable resource.
## API
Huge pages can be consumed via container level resource requirements using the
resource name `hugepages-<size>`, where size is the most compact binary notation
using integer values supported on a particular node. For example, if a node
supports 2048KiB page sizes, it will expose a schedulable resource
`hugepages-2Mi`. Unlike CPU or memory, huge pages do not support overcommit. Note
that when requesting hugepage resources, either memory or CPU resources must
be requested as well.
resource name `hugepages-<size>`, where `<size>` is the most compact binary
notation using integer values supported on a particular node. For example, if a
node supports 2048KiB and 1048576KiB page sizes, it will expose a schedulable
resources `hugepages-2Mi` and `hugepages-1Gi`. Unlike CPU or memory, huge pages
do not support overcommit. Note that when requesting hugepage resources, either
memory or CPU resources must be requested as well.
A pod may consume multiple huge page sizes in a single pod spec. In this case it
must use `medium: HugePages-<hugepagesize>` notation for all volume mounts.
```yaml
apiVersion: v1
kind: Pod
metadata:
name: huge-pages-example
spec:
containers:
- name: example
image: fedora:latest
command:
- sleep
- inf
volumeMounts:
- mountPath: /hugepages-2Mi
name: hugepage-2mi
- mountPath: /hugepages-1Gi
name: hugepage-1gi
resources:
limits:
hugepages-2Mi: 100Mi
hugepages-1Gi: 2Gi
memory: 100Mi
requests:
memory: 100Mi
volumes:
- name: hugepage-2mi
emptyDir:
medium: HugePages-2Mi
- name: hugepage-1gi
emptyDir:
medium: HugePages-1Gi
```
A pod may use `medium: HugePages` only if it requests huge pages of one size.
```yaml
apiVersion: v1
@@ -66,8 +105,7 @@ spec:
- Huge page requests must equal the limits. This is the default if limits are
specified, but requests are not.
- Huge pages are isolated at a pod scope, container isolation is planned in a
future iteration.
- Huge pages are isolated at a container scope, so each container has own limit on their cgroup sandbox as requested in a container spec.
- EmptyDir volumes backed by huge pages may not consume more huge page memory
than the pod request.
- Applications that consume huge pages via `shmget()` with `SHM_HUGETLB` must
@@ -75,10 +113,15 @@ spec:
- Huge page usage in a namespace is controllable via ResourceQuota similar
to other compute resources like `cpu` or `memory` using the `hugepages-<size>`
token.
- Support of multiple sizes huge pages is feature gated. It can be
enabled with the `HugePageStorageMediumSize` [feature
gate](/docs/reference/command-line-tools-reference/feature-gates/) on the {{<
glossary_tooltip text="kubelet" term_id="kubelet" >}} and {{<
glossary_tooltip text="kube-apiserver"
term_id="kube-apiserver" >}} (`--feature-gates=HugePageStorageMediumSize=true`).
## Future
- Support container isolation of huge pages in addition to pod isolation.
- NUMA locality guarantees as a feature of quality of service.
- LimitRange support.