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KServe Local Model Cache

By caching LLM models locally, the InferenceService startup time can be greatly improved. For deployments with more than one replica, the local persistent volume can serve multiple pods with the warmed up model cache.

  • LocalModelCache is a KServe custom resource to specify which model from persistent storage to cache on local storage of the kubernetes node.
  • LocalModelNodeGroup is a KServe custom resource to manage the node group for caching the models and the local persistent storage.
  • LocalModelNode is a KServe custom resource to track the status of the models cached on given local node.

In this example, we demonstrate how you can cache the models using Kubernetes nodes' local disk NVMe volumes from HF hub.

Create the LocalModelNodeGroup

Create the LocalModelNodeGroup using the local persistent volume with specified local NVMe volume path.

  • The storageClassName should be set to local-storage.
  • The nodeAffinity should be specified which nodes to cache the model using node selector.
  • Local path should be specified on PV as the local storage to cache the models. 
    apiVersion: serving.kserve.io/v1alpha1
kind: LocalModelNodeGroup
metadata:
  name: workers
spec:
  storageLimit: 1.7T
  persistentVolumeClaimSpec:
    accessModes:
      - ReadWriteOnce
    resources:
      requests:
        storage: 1700G
    storageClassName: local-storage
    volumeMode: Filesystem
    volumeName: models
  persistentVolumeSpec:
    accessModes:
      - ReadWriteOnce
    volumeMode: Filesystem
    capacity:
      storage: 1700G
    local:
      path: /models
    nodeAffinity:
       required:
         nodeSelectorTerms:
           - key: nvidia.com/gpu-product
             values:
               - NVIDIA-A100-SXM4-80GB

Configure Local Model Download Job Namespace

Before creating the LocalModelCache resource to cache the models, you need to make sure the credentials are configured in the download job namespace. The download jobs are created in the configured namespace kserve-localmodel-jobs. In this example we are caching the models from HF hub, so the HF token secret should be created pre-hand in the same namespace along with the storage container configurations.

Create the HF Hub token secret. 

apiVersion: v1
kind: Secret
metadata:
  name: hf-secret
  namespace: kserve-localmodel-jobs
type: Opaque
stringData:
  HF_TOKEN: xxxx # fill in the hf hub token

Create the HF Hub cluster storage container to refer to the HF Hub secret.

apiVersion: "serving.kserve.io/v1alpha1"
kind: ClusterStorageContainer
metadata:
  name: hf-hub
spec:
  container:
    name: storage-initializer
    image: kserve/storage-initializer:latest
    env:
    - name: HF_TOKEN  # Option 2 for authenticating with HF_TOKEN
      valueFrom:
        secretKeyRef:
          name: hf-secret
          key: HF_TOKEN
          optional: false
    resources:
      requests:
        memory: 100Mi
        cpu: 100m
      limits:
        memory: 1Gi
        cpu: "1"
  supportedUriFormats:
    - prefix: hf://
  workloadType: localModelDownloadJob

Create the LocalModelCache

Create the LocalModelCache to specify the source model storage URI to pre-download the models to local NVMe volumes for warming up the cache.

  • sourceModelUri is the model persistent storage location where to download the model for local cache.
  • nodeGroups is specified to indicate which nodes to cache the model.
apiVersion: serving.kserve.io/v1alpha1
kind: LocalModelCache
metadata:
  name: meta-llama3-8b-instruct
spec:
  sourceModelUri: hf://meta-llama/meta-llama-3-8b-instruct
  modelSize: 10Gi
  nodeGroups: 
  - workers

After LocalModelCache is created, KServe creates the download jobs on each node in the group to cache the model in local storage.

kubectl get jobs meta-llama3-8b-instruct-kind-worker  -n kserve-localmodel-jobs
NAME                                       STATUS     COMPLETIONS   DURATION   AGE
meta-llama3-8b-instruct-kind-worker   Complete   1/1           4m21s      5d17h

The download job is created using the provisioned PV/PVC. 

kubectl get pvc meta-llama3-8b-instruct  -n kserve-localmodel-jobs 
NAME                      STATUS   VOLUME                             CAPACITY   ACCESS MODES   STORAGECLASS    VOLUMEATTRIBUTESCLASS   AGE
meta-llama3-8b-instruct   Bound    meta-llama3-8b-instruct-download   10Gi       RWO            local-storage   <unset>                 9h

Check the LocalModelCache Status

LocalModelCache shows the model download status for each node in the group.

kubectl get localmodelcache meta-llama3-8b-instruct -oyaml

apiVersion: serving.kserve.io/v1alpha1
kind: LocalModelCache
metadata:
  name: meta-llama3-8b-instruct
spec:
  modelSize: 10Gi
  nodeGroup: workers
  sourceModelUri: hf://meta-llama/meta-llama-3-8b-instruct
status:
  copies:
    available: 1
    total: 1
  nodeStatus:
    kind-worker: NodeDownloaded

LocalModelNode shows the model download status of each model expected to cache on the given node.

kubectl get localmodelnode kind-worker -oyaml

apiVersion: serving.kserve.io/v1alpha1
kind: LocalModelNode
metadata:
  name: kind-worker
spec:
  localModels:
    - modelName: meta-llama3-8b-instruct
      sourceModelUri: hf://meta-llama/meta-llama-3-8b-instruct
status:
  modelStatus:
    meta-llama3-8b-instruct: ModelDownloaded

Deploy InferenceService using the LocalModelCache

Finally you can deploy the LLMs with InferenceService using the local model cache if the model has been previously cached using the LocalModelCache resource by matching the model storage URI.

The model cache is currently disabled by default. To enable, you need to modify the localmodel.enabled field on the inferenceservice-config ConfigMap.

kubectl apply -f - <<EOF
apiVersion: serving.kserve.io/v1beta1
kind: InferenceService
metadata:
  name: huggingface-llama3
spec:
  predictor:
    model:
      modelFormat:
        name: huggingface
      args:
        - --model_name=llama3
        - --model_id=meta-llama/meta-llama-3-8b-instruct
      storageUri: hf://meta-llama/meta-llama-3-8b-instruct
      resources:
        limits:
          cpu: "6"
          memory: 24Gi
          nvidia.com/gpu: "1"
        requests:
          cpu: "6"
          memory: 24Gi
          nvidia.com/gpu: "1"
EOF
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