Description

Observed Behavior:

I have a few NodePools that I'm using in a "partitioned" manner. Basically, each NodePool is made independent using user-defined requirements & taints, and Pods in different namespaces use different Nodepools.

apiVersion: karpenter.sh/v1beta1
kind: NodePool
metadata:
  name: one
spec:
   taints:
        - key: example.com/partition-key
          value: one
          effect: NoSchedule
   requirements:
    - key: example.com/partition-key
      operator: In
      values: ["one"]
---
apiVersion: karpenter.sh/v1beta1
kind: NodePool
metadata:
  name: two
spec:
   taints:
        - key: example.com/partition-key
          value: two
          effect: NoSchedule
   requirements:
    - key: example.com/partition-key
      operator: In
      values: ["two"]

This works fine for the most part, but I'm observing issues with multi-node consolidation.

As far as I can tell, multi-node consolidation looks at all deprovisionable Nodes together:
https://github.com/kubernetes-sigs/karpenter/blob/cc54b340f630b46a26d19a3cbd49d90c8b3a6d45/pkg/controllers/disruption/multinodeconsolidation.go#L44C42-L44C42

Which I think means there's no multi-node consolidation happening (or it's sub-optimal at best). Shouldn't this be done on groups of compatible NodePools independently?

Another place where I think this is a problem is when simulating the scheduling you look at all Pending Pods:
https://github.com/kubernetes-sigs/karpenter/blob/cc54b340f630b46a26d19a3cbd49d90c8b3a6d45/pkg/controllers/disruption/helpers.go#L97C35-L97C35

But if one of those Pending Pods is not compatible with the firstN candidates chosen from all Nodes, then simulation will always complain about unschedulable Pods (highly likely as the number of nodes/paritions increase)

Expected Behavior:

NodePools should be consolidated in groups computed based on their requirements or based on some configurable partition key.

Reproduction Steps (Please include YAML): See above

Versions:

• Chart Version: v0.33.0
• Kubernetes Version (kubectl version): 1.27

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