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Merge pull request #51068 from jmencak/4.12-thp
OCPBUGS-1849: Move section about disabling Transparent Huge Pages
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‎modules/disabling-transparent-huge-pages.adoc

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// Module included in the following assemblies:
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//
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// * scalability_and_performance/what-huge-pages-do-and-how-they-are-consumed-by-apps.adoc
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:_content-type: PROCEDURE
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[id="disable-thp_{context}"]
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= Disabling Transparent Huge Pages
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Transparent Huge Pages (THP) attempt to automate most aspects of creating, managing, and using huge pages. Since THP automatically manages the huge pages, this is not always handled optimally for all types of workloads. THP can lead to performance regressions, since many applications handle huge pages on their own. Therefore, consider disabling THP. The following steps describe how to disable THP using the Node Tuning Operator (NTO).
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.Procedure
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. Create a file with the following content and name it `thp-disable-tuned.yaml`:
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[source,yaml]
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----
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apiVersion: tuned.openshift.io/v1
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kind: Tuned
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metadata:
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name: thp-workers-profile
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namespace: openshift-cluster-node-tuning-operator
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spec:
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profile:
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- data: |
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[main]
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summary=Custom tuned profile for OpenShift to turn off THP on worker nodes
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include=openshift-node
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[vm]
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transparent_hugepages=never
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name: openshift-thp-never-worker
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recommend:
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- match:
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- label: node-role.kubernetes.io/worker
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priority: 25
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profile: openshift-thp-never-worker
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----
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. Create the Tuned object:
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[source,terminal]
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----
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$ oc create -f thp-disable-tuned.yaml
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----
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. Check the list of active profiles:
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[source,terminal]
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----
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$ oc get profile -n openshift-cluster-node-tuning-operator
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----
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.Verification
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* Log in to one of the nodes and do a regular THP check to verify if the nodes applied the profile successfully:
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[source,terminal]
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----
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$ cat /sys/kernel/mm/transparent_hugepage/enabled
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----
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.Example output
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[source,terminal]
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----
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always madvise [never]
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----

‎modules/how-huge-pages-are-consumed-by-apps.adoc

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* Applications that consume huge pages via `shmget()` with `SHM_HUGETLB` must run
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with a supplemental group that matches *_proc/sys/vm/hugetlb_shm_group_*.
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[role="_additional-resources"]
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.Additional resources
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* link:https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/performance_tuning_guide/sect-red_hat_enterprise_linux-performance_tuning_guide-configuring_transparent_huge_pages[Configuring Transparent Huge Pages]

‎modules/ibm-z-disable-thp.adoc

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//
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// * scalability_and_performance/ibm-z-recommended-host-practices.adoc
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:_content-type: PROCEDURE
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:_content-type: CONCEPT
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[id="ibm-z-disable-thp_{context}"]
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= How to disable Transparent Huge Pages
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Transparent Huge Pages (THP) attempt to automate most aspects of creating, managing, and using huge pages. Since THP automatically manages the huge pages, this is not always handled optimally for all types of workloads. THP can lead to performance regressions, since many applications handle huge pages on their own. Therefore, consider disabling THP. The following steps describe how to disable THP using a Node Tuning Operator (NTO) profile.
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[id="disable-thp-with-a-nto-profile_{context}"]
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== Disable THP with a Node Tuning Operator (NTO) profile
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.Procedure
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. Copy the following NTO sample profile into a YAML file. For example, `thp-s390-tuned.yaml`:
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+
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[source,yaml]
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----
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apiVersion: tuned.openshift.io/v1
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kind: Tuned
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metadata:
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name: thp-workers-profile
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namespace: openshift-cluster-node-tuning-operator
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spec:
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profile:
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- data: |
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[main]
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summary=Custom tuned profile for OpenShift on IBM Z to turn off THP on worker nodes
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include=openshift-node
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[vm]
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transparent_hugepages=never
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name: openshift-thp-never-worker
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recommend:
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- match:
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- label: node-role.kubernetes.io/worker
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priority: 35
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profile: openshift-thp-never-worker
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----
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. Create the NTO profile:
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[source,terminal]
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----
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$ oc create -f thp-s390-tuned.yaml
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----
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. Check the list of active profiles:
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[source,terminal]
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----
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$ oc get tuned -n openshift-cluster-node-tuning-operator
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----
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. Remove the profile:
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[source,terminal]
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----
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$ oc delete -f thp-s390-tuned.yaml
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----
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.Verification
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* Log in to one of the nodes and do a regular THP check to verify if the nodes applied the profile successfully:
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[source,terminal]
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----
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$ cat /sys/kernel/mm/transparent_hugepage/enabled
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always madvise [never]
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----
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= Disable Transparent Huge Pages
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Transparent Huge Pages (THP) attempt to automate most aspects of creating, managing, and using huge pages. Since THP automatically manages the huge pages, this is not always handled optimally for all types of workloads. THP can lead to performance regressions, since many applications handle huge pages on their own. Therefore, consider disabling THP.

‎scalability_and_performance/what-huge-pages-do-and-how-they-are-consumed-by-apps.adoc

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* xref:../nodes/containers/nodes-containers-downward-api.adoc#nodes-containers-downward-api[Allowing containers to consume Downward API objects]
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include::modules/configuring-huge-pages.adoc[leveloffset=+1]
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include::modules/disabling-transparent-huge-pages.adoc[leveloffset=+1]

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