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[release-4.21] OCPBUGS-78201: kubelet: Less aggressive low memory reservation#5756

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openshift-merge-bot[bot] merged 1 commit intoopenshift:release-4.21from
openshift-cherrypick-robot:cherry-pick-5716-to-release-4.21
Mar 13, 2026
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[release-4.21] OCPBUGS-78201: kubelet: Less aggressive low memory reservation#5756
openshift-merge-bot[bot] merged 1 commit intoopenshift:release-4.21from
openshift-cherrypick-robot:cherry-pick-5716-to-release-4.21

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@openshift-cherrypick-robot openshift-cherrypick-robot commented Mar 10, 2026

This is an automated cherry-pick of #5716

/assign sdodson

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kubelet: Less aggressive low memory reservation
cfb23f2 
Out of the box a standard OpenShift worker has about 3000 Mi of unevictable
workload. Thus when we reserve 2GiB on an 8GiB instance that node will not
autoscale down because it never drops below the 50% usage threshold.

Therefore, lets reduce the system reserved on the lowest end. The assumption
here is that nodes this small are less likely to run the full 250 pods and
actually consume the full set of resources. We should make sure that this
aligns with our understanding of the problem we're trying to solve by enabling
dynamic resource reservation in the first place, which I believe is the fact
that massive nodes were only getting 1GiB of reserved memory despite running
hundreds of pods.

Here's the difference in memory reservation at common sizes :

| Total | Old Reserved | New Reserved |
| ----- | ------------ | ------------ |
| 8     | 2            | 1            |
| 16    | 3            | 1.48         |
| 32    | 4            | 2.44         |
| 64    | 5            | 4.36         |
| 128   | 9            | 8.2          |
| 256   | 12           | 10.44        |
| 512   | 17           | 15.56        |
| 1024  | 27           | 25.8         |
| 2048  | 48           | 46.28        |
@openshift-cherrypick-robot openshift-cherrypick-robot mentioned this pull request Mar 10, 2026
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openshift-ci-robot commented Mar 10, 2026

@openshift-cherrypick-robot: Jira Issue OCPBUGS-75869 has been cloned as Jira Issue OCPBUGS-78201. Will retitle bug to link to clone.
/retitle [release-4.21] OCPBUGS-78201: kubelet: Less aggressive low memory reservation

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This is an automated cherry-pick of #5716

/assign sdodson

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@openshift-ci openshift-ci bot changed the title [release-4.21] OCPBUGS-75869: kubelet: Less aggressive low memory reservation [release-4.21] OCPBUGS-78201: kubelet: Less aggressive low memory reservation Mar 10, 2026
@openshift-ci-robot openshift-ci-robot added jira/valid-reference Indicates that this PR references a valid Jira ticket of any type. jira/invalid-bug Indicates that a referenced Jira bug is invalid for the branch this PR is targeting. labels Mar 10, 2026
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openshift-ci-robot commented Mar 10, 2026

@openshift-cherrypick-robot: This pull request references Jira Issue OCPBUGS-78201, which is invalid:

  • release note text must be set and not match the template OR release note type must be set to "Release Note Not Required". For more information you can reference the OpenShift Bug Process.
  • expected dependent Jira Issue OCPBUGS-75869 to be in one of the following states: VERIFIED, RELEASE PENDING, CLOSED (ERRATA), CLOSED (CURRENT RELEASE), CLOSED (DONE), CLOSED (DONE-ERRATA), but it is MODIFIED instead

Comment /jira refresh to re-evaluate validity if changes to the Jira bug are made, or edit the title of this pull request to link to a different bug.

The bug has been updated to refer to the pull request using the external bug tracker.

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In response to this:

This is an automated cherry-pick of #5716

/assign sdodson

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@openshift-ci openshift-ci bot requested review from djoshy and dkhater-redhat March 10, 2026 22:39
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openshift-ci bot commented Mar 11, 2026

@openshift-cherrypick-robot: all tests passed!

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sdodson commented Mar 13, 2026

/jira refresh

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openshift-ci-robot commented Mar 13, 2026

@sdodson: This pull request references Jira Issue OCPBUGS-78201, which is invalid:

  • release note text must be set and not match the template OR release note type must be set to "Release Note Not Required". For more information you can reference the OpenShift Bug Process.

Comment /jira refresh to re-evaluate validity if changes to the Jira bug are made, or edit the title of this pull request to link to a different bug.

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sdodson commented Mar 13, 2026

/jira refresh

@openshift-ci-robot openshift-ci-robot added jira/valid-bug Indicates that a referenced Jira bug is valid for the branch this PR is targeting. and removed jira/invalid-bug Indicates that a referenced Jira bug is invalid for the branch this PR is targeting. labels Mar 13, 2026
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openshift-ci-robot commented Mar 13, 2026

@sdodson: This pull request references Jira Issue OCPBUGS-78201, which is valid. The bug has been moved to the POST state.

7 validation(s) were run on this bug
  • bug is open, matching expected state (open)
  • bug target version (4.21.z) matches configured target version for branch (4.21.z)
  • bug is in the state New, which is one of the valid states (NEW, ASSIGNED, POST)
  • release note text is set and does not match the template
  • dependent bug Jira Issue OCPBUGS-75869 is in the state Verified, which is one of the valid states (VERIFIED, RELEASE PENDING, CLOSED (ERRATA), CLOSED (CURRENT RELEASE), CLOSED (DONE), CLOSED (DONE-ERRATA))
  • dependent Jira Issue OCPBUGS-75869 targets the "4.22.0" version, which is one of the valid target versions: 4.22.0
  • bug has dependents

Requesting review from QA contact:
/cc @lyman9966

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@openshift-ci openshift-ci bot requested a review from lyman9966 March 13, 2026 16:02
@sdodson sdodson added lgtm Indicates that a PR is ready to be merged. approved Indicates a PR has been approved by an approver from all required OWNERS files. backport-risk-assessed Indicates a PR to a release branch has been evaluated and considered safe to accept. labels Mar 13, 2026
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sdodson commented Mar 13, 2026

/verified by @sdodson

@openshift-ci-robot openshift-ci-robot added the verified Signifies that the PR passed pre-merge verification criteria label Mar 13, 2026
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@sdodson: This PR has been marked as verified by @sdodson.

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/verified by @sdodson

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openshift-ci bot commented Mar 13, 2026

[APPROVALNOTIFIER] This PR is APPROVED

Approval requirements bypassed by manually added approval.

This pull-request has been approved by: openshift-cherrypick-robot

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@openshift-merge-bot openshift-merge-bot bot merged commit 11e313d into openshift:release-4.21 Mar 13, 2026
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openshift-ci-robot commented Mar 13, 2026

@openshift-cherrypick-robot: Jira Issue Verification Checks: Jira Issue OCPBUGS-78201
✔️ This pull request was pre-merge verified.
✔️ All associated pull requests have merged.
✔️ All associated, merged pull requests were pre-merge verified.

Jira Issue OCPBUGS-78201 has been moved to the MODIFIED state and will move to the VERIFIED state when the change is available in an accepted nightly payload. 🕓

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In response to this:

This is an automated cherry-pick of #5716

/assign sdodson

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