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Kubernetes v1.20 [stable]
Kubernetes supports the allocation and consumption of pre-allocated huge pages by applications in a Pod. This page describes how users can consume huge pages.
Before you begin
- Kubernetes nodes must pre-allocate huge pages in order for the node to report 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 schedulable resources.
Huge pages can be consumed via container level resource requirements using the
<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
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
medium: HugePages-<hugepagesize> notation for all volume mounts.
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.
apiVersion: v1 kind: Pod metadata: name: huge-pages-example spec: containers: - name: example image: fedora:latest command: - sleep - inf volumeMounts: - mountPath: /hugepages name: hugepage resources: limits: hugepages-2Mi: 100Mi memory: 100Mi requests: memory: 100Mi volumes: - name: hugepage emptyDir: medium: HugePages
- 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 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
SHM_HUGETLBmust run with a supplemental group that matches
- Huge page usage in a namespace is controllable via ResourceQuota similar
to other compute resources like
- Support of multiple sizes huge pages is feature gated. It can be
disabled with the
HugePageStorageMediumSizefeature gate on the kubelet and kube-apiserver (