CPU QoS

Limits

The following table describes the versions of the system components that are required for using the CPU QoS feature.

Procedure

1. Create a ConfigMap named ack-slo-manager-config based on the following content:

   # Example of the ack-slo-manager-config ConfigMap. 
   apiVersion: v1
   kind: ConfigMap
   metadata:
     name: ack-slo-manager-config
     namespace: kube-system
   data:
     #Enable the CPU QoS feature. 
     resource-qos-config: |
       {
         "clusterStrategy": {
           "lsClass": {
             "cpuQOS": {
               "enable": true,
               "groupIdentity": 2
             }
           },
           "beClass": {
             "cpuQOS": {
               "enable": true,
               "groupIdentity": -1
             }
           }
         }
       }

   Specify lsClass and beClass to assign the LS and BE classes to different pods. cpuQOS includes the CPU QoS parameters. The following table describes the parameters.

   Parameter	Type	Valid value	Description
   enable	Boolean	true false	true: enables the CPU QoS feature for all containers in the cluster. false: disables the CPU QoS feature for all containers in the cluster.
   groupIdentity	Int	-1~2	Specify group identities for CPU scheduling. By default, the group identity of LS pods is 2 and the group identity of BE pods is -1. A value of 0 indicates that no group identity is assigned. A greater group identity value indicates a higher priority in CPU scheduling. For example, you can set cpu.bvt_warp_ns=2 for LS pods and set cpu.bvt_warp_ns=-1 for BE pods because the priority of LS pods is higher than that of BE pods. For more information, see Group identity feature.

   Note If alibabacloud.com/qosClass is not specified for a pod, the ack-slo-manager component configures the pod based on the original QoS class of the pod. The component uses the BE settings in the preceding ConfigMap if the original QoS class is BE. The component uses the LS settings in the preceding ConfigMap if the original QoS class is not BE.
2. Run the following command to enable the CPU QoS feature for all containers in the cluster.
   To avoid changing other settings in the ConfigMap, we commend that you run the kubectl patch command to update the ConfigMap.

   kubectl patch cm -n kube-system ack-slo-manager-config --patch "$(cat configmap.yaml)"

3. Create a file named ls-pod-demo.yaml based on the following YAML content:

   apiVersion: v1
   kind: Pod
   metadata:
     name: ls-pod-demo
     annotations:
       alibabacloud.com/qosClass: 'LS' #Set the QoS class of the pod to LS. 
   spec:
     containers:
     - command:
       - httpd
       - -D
       - FOREGROUND
       image: registry.cn-zhangjiakou.aliyuncs.com/acs/apache-2-4-51-for-slo-test:v0.1
       imagePullPolicy: Always
       name: apache
       resources:
         limits:
           cpu: "4"
           memory: 10Gi
         requests:
           cpu: "4"
           memory: 10Gi
     restartPolicy: Never
     schedulerName: default-scheduler

4. Run the following command to deploy the ls-pod-demo pod in the cluster:

   kubectl apply -f ls-pod-demo.yaml

5. Run the following command to check whether the CPU group identity of the LS pod in the control group (cgroup) of the node takes effect:

   cat /sys/fs/cgroup/cpu/kubepods.slice/kubepods-pod1c20f2ad****.slice/cpu.bvt_warp_ns

   Expected output:

   #The group identity of the LS pod is 2 (high priority). 
   2

6. Create a file named be-pod-demo.yaml based on the following content:

   apiVersion: v1
   kind: Pod
   metadata:
     name: be-pod-demo
     annotations:
       alibabacloud.com/qosClass: 'BE' #Set the QoS class of the pod to BE. 
   spec:
     containers:
       - args:
           - '-c'
           - '1'
           - '--vm'
           - '1'
         command:
           - stress
         image: polinux/stress
         imagePullPolicy: Always
         name: stress
     restartPolicy: Always
     schedulerName: default-scheduler

7. Run the following command to deploy the be-pod-demo pod in the cluster:

   kubectl apply -f be-pod-demo.yaml

8. Run the following command to check whether the CPU group identity of the BE pod in the cgroup of the node takes effect:

   cat /sys/fs/cgroup/cpu/kubepods.slice/kubepods-besteffort.slice/kubepods-besteffort-pod4b6e96c8****.slice/cpu.bvt_warp_ns

   Expected output:

   #The group identity of the BE pod is -1 (low priority). 
   -1

   The output shows that the priority of the LS pod is high and the priority of the BE pod is low. CPU resources are preferably scheduled to the LS pod to ensure the service quality.