How to configure huge pages for pod?

Recently, I build a Kubernetes AI Assistant(chat bot) with knowledge from kubernetes docs website using RAG technology. And I ask this assistant a common question for test case. The result is well performed.

Here is the result from the assistant:

To configure huge pages for a Pod in Kubernetes, you need to follow these steps:

1. Ensure that your Kubernetes nodes have pre-allocated huge pages. This is done by configuring the GRUB_CMDLINE_LINUX parameter in the /etc/default/grub file on each node. For example, you can allocate 2*1GiB of 1 GiB and 512*2MiB of 2 MiB pages with the following configuration:

   GRUB_CMDLINE_LINUX="hugepagesz=1G hugepages=2 hugepagesz=2M hugepages=512"

After updating the configuration file, you need to reboot the nodes for the changes to take effect.

2. In your Pod manifest, specify the required huge page resources under the resources section. Here’s an example:

   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

In this example, the Pod is requesting 100Mi of 2 MiB huge pages (hugepages-2Mi) and 2Gi of 1 GiB huge pages (hugepages-1Gi). It also requests 100Mi of regular memory.

3. Apply the Pod manifest using the kubectl apply command:

   kubectl apply -f pod.yaml

Kubernetes will schedule the Pod to a node that has the pre-allocated huge pages available. You can verify the allocation by describing the Pod or the Node.

   kubectl describe pod huge-pages-example
   kubectl describe node <node-name>

Look for the Allocatable section in the output to see the allocated huge page resources.

Note: For dynamically allocated pages after boot, you need to restart the Kubelet for the new allocations to be reflected.

I hope this helps! Let me know if you have any further questions.

And then i ask the same question to ChatGPT:

Configuring huge pages for a pod in Kubernetes involves several steps. Huge pages can improve performance for applications that require large amounts of memory by reducing the overhead of managing large memory blocks. Here’s a general overview of how you can configure huge pages for a pod:

1. Enable Huge Pages in the Kernel: Ensure that huge pages are enabled in the kernel of your Kubernetes nodes. This usually involves setting the appropriate kernel parameters and rebooting the nodes.
2. Define a Huge Page Pool: You need to configure a huge page pool on your Kubernetes nodes. This involves setting up a mount point for huge pages and configuring the number of huge pages available.
3. Update the Pod Specification:

• Add a resource request for huge pages in your pod specification. Specify the amount of huge pages you want to reserve for your pod.
• For example, to request 1 GiB of huge pages, you would add:
  yaml resources: requests: hugepages-1Gi: "1Gi"

1. Modify Security Context (if necessary): Depending on your Kubernetes setup, you might need to modify the security context of your pod to allow it to use huge pages. This might involve setting the SYS_ADMIN capability.
2. Deploy the Pod: Once you’ve updated your pod specification, deploy your pod to the Kubernetes cluster. Kubernetes will try to schedule the pod on a node that has enough huge pages available.
3. Verify Huge Page Usage: After the pod is running, you can verify that it is using huge pages by inspecting the pod’s details and looking for the hugepages-1Gi resource.

Please note that the exact steps and configuration details may vary depending on your Kubernetes setup and the specifics of your application.

To Summary

For domain specific knowledge, using RAG maybe a better choice. The assistant responsed with the knowledge provided which comes from the kubernetes docs. You can explore the assistant here: https://aiconfer.com/explore/assistants/bb170a91-d313-4a99-adb7-6aad5a5ccec1