How to use CPU Nodes

How to Add CPU Nodes and Set Up CPU-only VC

In current release, support for CPU nodes is limited. The installation guide won't work if you only have CPU worker nodes. However, after you set up the cluster with GPU worker nodes, you can add CPU worker nodes and CPU-only virtual cluster. This section is a detailed guide.

Adding CPU nodes is not much different from adding GPU nodes, as we have described in How to Add and Remove Nodes. So you can follow that document basically. Meanwhile, there are two differences for CPU-only nodes:

In the preparation phase, you don't need to check GPU driver and nvidia-container-runtime.

In the hived scheduler setting, you should omit gpu field or use gpu: 0 in skuTypes for your CPU-only VCs. Don't mix CPU nodes with GPU nodes. Here is an example:

hivedscheduler:
config: |
  physicalCluster:
    skuTypes:
      K80:
        gpu: 1
        cpu: 5
        memory: 56334Mi
      CPU:
        cpu: 1
        memory: 10240Mi
    cellTypes:
      K80-NODE:
        childCellType: K80
        childCellNumber: 4
        isNodeLevel: true
      K80-NODE-POOL:
        childCellType: K80-NODE
        childCellNumber: 2
      CPU-NODE:
        childCellType: CPU
        childCellNumber: 8
        isNodeLevel: true
      CPU-NODE-POOL:
        childCellType: CPU-NODE
        childCellNumber: 1
    physicalCells:
    - cellType: K80-NODE-POOL
      cellChildren:
      - cellAddress: k80-worker1
      - cellAddress: k80-worker1
    - cellType: FAKE-NODE-POOL
      cellChildren:
      - cellAddress: cpu-worker1
  virtualClusters:
    default:
      virtualCells:
      - cellType: K80-NODE-POOL.K80-NODE
        cellNumber: 2
    cpu:
      virtualCells:
      - cellType: CPU-NODE-POOL.CPU-NODE
        cellNumber: 1

Explanation of the above example: Supposing we have a node named cpu-worker1 in Kubernetes. It has 80GB memory and 8 allocatable CPUs (please use kubectl describe cpu-worker1 to confirm the allocatable resources). Then, in skuTypes, we can set a CPU sku, which has 1 CPU and 10240 MB (80GB / 8) memory. You can reserve some memory or CPUs if you want. CPU-NODE and CPU-NODE-POOL are set correspondingly in the cellTypes. Finally, the setting will result in one default VC and one cpu VC. The cpu VC contains one CPU node.

Submit CPU-only Jobs

If you want to submit a CPU-only job, please submit it directly to the CPU-only VC. A special requirement is that, you should use exactly the same GPU number as the CPU number you want. For example, if you want to use 8 CPUs, you should set 8 GPUs and 8 CPUs as follows:

This requirement may be fixed in the future.