Document URL: CNV-2.3/OCP4.4 Section Number and Name: Describe the issue: Use could end up with incorrect hugepages configuration and we would like to have a documentation for this feature. A bug was raised, with unexpected behaviour. https://bugzilla.redhat.com/show_bug.cgi?id=1822875 Suggestions for improvement: We, would want to have documentation, to address the hugepages expected behavior here. Additional information:
User could end up with incorrect hugepages configuration and we would like to have a documentation for this feature.
Current upstream documentation around hugepages is, https://kubevirt.io/2018/Kubevirt-v0.7.0.html From the bug, https://bugzilla.redhat.com/show_bug.cgi?id=1822875#c14 Was expecting, "HugePages_Total: 2", but we got "HugePages_Total: 1" Memory/RAM was specified as 4Gi in VM spec file and we see it as approx 4Gi (3.7G) as seen from above "free -h", in comment 12.
@Nelly, yes. OpenShift docs cover the node side for pre-allocating hugepages: https://docs.openshift.com/container-platform/4.4/scalability_and_performance/what-huge-pages-do-and-how-they-are-consumed-by-apps.html#configuring-huge-pages_huge-pages The work for this then is defining it in the VM config, and the the upstream doc for that looks good. We can do this for 2.4. I've updated the flag.
Moving to ON_QA but adding need_info on Kedar for attention in case he would like to review. I have drafted some content to cover configuring VM to use huge pages: PR: https://github.com/openshift/openshift-docs/pull/23705/files Build: https://cnv-bz1845198-hugepages--ocpdocs.netlify.app/openshift-enterprise/latest/virt/virtual_machines/advanced_vm_management/virt-using-huge-pages-with-vms.html Please note, the 'What huge pages do' module is reused from OpenShift docs - I've just conditionalises the final line so that it referes to VMs instead of Pods.
The hugepages docs PR was merged: https://github.com/openshift/openshift-docs/pull/23705 I will add a link to the docs when they are published for 2.4
This was published with the OpenShift Virtualization 2.4 release. You can view the content here: https://docs.openshift.com/container-platform/4.5/virt/virtual_machines/advanced_vm_management/virt-using-huge-pages-with-vms.html