kubernetes-csi/external-provisioner

Reduce CentralCapacityController workque depth by filtering allowed topologies in storage class

yuxiang-he opened this issue · 3 comments

yuxiang-he commented

Is your feature request related to a problem?/Why is this needed

See onSCAddOrUpdate implementation in https://github.com/kubernetes-csi/external-provisioner/blob/v4.0.0/pkg/capacity/capacity.go#L378-L384

	segments := c.topologyInformer.List()

	c.capacitiesLock.Lock()
	defer c.capacitiesLock.Unlock()
	for _, segment := range segments {
		c.addWorkItem(segment, sc)
	}

Currently the capacity controller creates a workqueue item for every segment x storageClass combination, some of which are impossible.

Describe the solution you'd like in detail

Storage classes can specify allowed topologies https://kubernetes.io/docs/concepts/storage/storage-classes/#allowed-topologies so not all combinations of segment x storageClass are valid here. An example would be certain types of storage (and hence storage class) are only available in selected topology segments.

We can reduce potential workqueue cardinality by filtering out impossible segment x storageClass combinations. This allows quicker CSIStorageCapacity object updates.

Describe alternatives you've considered

Additional context

yuxiang-he commented

This is another issue discovered while investigating #1161

pohly commented

This makes sense to me.

/triage accepted
/help

k8s-ci-robot commented

@pohly:
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In response to this:

This makes sense to me.

/triage accepted
/help

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