Update Alpha requirements for 1.34. Make CPU PSI a Beta requirement.

Author: roycaihw

keps/prod-readiness/sig-node/5394.yaml

@@ -0,0 +1,6 @@
+# The KEP must have an approver from the
+# "prod-readiness-approvers" group
+# of http://git.k8s.io/enhancements/OWNERS_ALIASES
+kep-number: 5394
+alpha:
+  approver: "@johnbelamaric"

keps/sig-node/5394-psi-node-conditions/README.md

@@ -115,22 +115,22 @@ default threshold to be used for reporting the nodes under heavy resource pressu
 
 **Note:** These actions are tentative, and will depend on different the outcome from testing and discussions with sig-node members, users, and other folks. 
 
+**Note:** In the initial Alpha implementation, we are not introducing node pressure condition for CPU. This is because unlike memory and IO, CPU is a compressible resource. See https://github.com/kubernetes/enhancements/issues/5062 for more details.
+
 1. Introduce a new kubelet config parameter, pressure threshold, to let users specify the pressure percentage beyond which the kubelet would report the node condition to disallow workloads to be scheduled on it.
 
-2. Add new node conditions corresponding to high PSI (beyond threshold levels) on CPU, Memory and IO.
+2. Add new node conditions corresponding to high PSI (beyond threshold levels) on Memory and IO.
 
 ```go
 // These are valid conditions of the node. Currently, we don't have enough information to decide
 // node condition.
 const (
 …
 	// Conditions based on pressure at system level cgroup.
-	NodeSystemCPUContentionPressure    NodeConditionType = "SystemCPUContentionPressure"
 	NodeSystemMemoryContentionPressure NodeConditionType = "SystemMemoryContentionPressure"
 	NodeSystemDiskContentionPressure   NodeConditionType = "SystemDiskContentionPressure"
 
 	// Conditions based on pressure at kubepods level cgroup.
-	NodeKubepodsCPUContentionPressure    NodeConditionType = "KubepodsCPUContentionPressure"
 	NodeKubepodsMemoryContentionPressure NodeConditionType = "KubepodsMemoryContentionPressure"
 	NodeKubepodsDiskContentionPressure   NodeConditionType = "KubepodsDiskContentionPressure"
 )
@@ -232,12 +232,22 @@ https://storage.googleapis.com/k8s-triage/index.html
 We expect no non-infra related flakes in the last month as a GA graduation criteria.
 -->
 
-- <test>: <link to test coverage>
+Test plan:
+- Enable the feature gate.
+- For each of memory and IO
+  - Schedule workloads to a node that overwhelms the resource.
+  - Ensure the node is marked with corresponding PSI pressure node condition and taint.
+  - Create more workloads and observe that the workloads cannot be scheduled onto this node.
+  - Delete existing workloads to free up the resource.
+  - Ensure the node condition and taint are removed.
+  - Create more workloads and observe the the workloads can be scheduled.
+  - Clean up.
 
 ### Graduation Criteria
 
 #### Alpha
 
+- Conduct experiments to decide the scope of the node condition (system v.s. kubepods v.s. node) as well as the default threshold
 - Enables kubelet to 
 report node conditions based off PSI values.
 - Initial e2e tests completed and enabled if CRI implementation supports
@@ -246,6 +256,7 @@ it.
 
 #### Beta
 
+- Decide whether CPU PSI will be used for node conditions.
 - Feature gate is enabled by default.
 - Extend e2e test coverage.
 - Allowing time for feedback.
@@ -566,6 +577,7 @@ NA
 
 - 2023/09/13: Initial proposal
 - 2025/06/11: Only keep Phase 2 contents in this new KEP. Phase 1 contents are kept in the original KEP.
+- 2025/06/11: Update Alpha requirements. Make CPU PSI a Beta requirement.
 
 ## Drawbacks
 

keps/sig-node/5394-psi-node-conditions/kep.yaml

@@ -1,13 +1,14 @@
 title: PSI based Node Conditions
-kep-number: 4205
+kep-number: 5394
 authors:
   - "@ndixita"
   - "@dragoncell"
+  - "@roycaihw"
 owning-sig: sig-node
 participating-sigs:
   - sig-node
 status: implementable
-creation-date: 2023-05-25
+creation-date: 2025-06-11
 reviewers:
   - "@mrunalp"
   - "@haircommander"
@@ -26,11 +27,11 @@ stage: alpha
 # The most recent milestone for which work toward delivery of this KEP has been
 # done. This can be the current (upcoming) milestone, if it is being actively
 # worked on.
-latest-milestone: "v1.33"
+latest-milestone: "v1.34"
 
 # The milestone at which this feature was, or is targeted to be, at each stage.
 milestone:
-  alpha: "v1.33"
+  alpha: "v1.34"
 
 # The following PRR answers are required at alpha release
 # List the feature gate name and the components for which it must be enabled