kubernetes從入門到精通系列目錄：

起始值 requests 最低保障

終結值 limits 硬限制

• CPU

<code>1 顆 CPU = 1000 millicores
0.5 顆 CPU = 500 m
/<code>

• 內存

<code>Ei、Pi、Ti、Gi、Mi、Ki
/<code>

19.1 資源限制

• 清單格式，詳見：kubectl explain pods.spec.containers.resources

<code>resources      <object>               # 資源限制
  limits       /<object>/<code>

• 清單示例，node 節點的 CPU 為 12 核心，cpu limits 設置為 1000m 也就是允許

<code>apiVersion: v1
kind: Pod
metadata:
  name: pod-resources-demo
  namespace: default
  labels:
    app: myapp
    tier: frontend
spec:
  containers:
  - name: nginx
    image: ikubernetes/stress-ng
    command:
    - "/usr/bin/stress-ng"
    #- "-m 1"                       # 以單線程壓測內存
    - "-c 1"                        # 以單線程壓測CPU
    - "--metrics-brief"
    ports:
    - name: http
      containerPort: 80
    - name: https
      containerPort: 443
    resources:
      requests:
        cpu: 1000m                 # 它決定在預選階段淘汰哪些主機
        memory: 512Mi
      limits:
        cpu: 1000m                 # 表示限制容器使用 node 節點的一顆 CPU，無論多少進程，它們最多隻能佔用 node 節點的可 CPU
        memory: 512Mi
/<code>

• 查看結果

<code>Mem: 855392K used, 139916K free, 10188K shrd, 796K buff, 350368K cached
CPU0:   0% usr   0% sys   0% nic  99% idle   0% io   0% irq   0% sirq
CPU1: 100% usr   0% sys   0% nic   0% idle   0% io   0% irq   0% sirq         # 佔滿了一顆 CPU 

CPU2:   0% usr   0% sys   0% nic  99% idle   0% io   0% irq   0% sirq
CPU3:   0% usr   0% sys   0% nic  99% idle   0% io   0% irq   0% sirq
CPU4:   0% usr   0% sys   0% nic  99% idle   0% io   0% irq   0% sirq
CPU5:   0% usr   0% sys   0% nic  99% idle   0% io   0% irq   0% sirq
CPU6:   0% usr   0% sys   0% nic  99% idle   0% io   0% irq   0% sirq
CPU7:   0% usr   0% sys   0% nic  99% idle   0% io   0% irq   0% sirq
CPU8:   0% usr   0% sys   0% nic  99% idle   0% io   0% irq   0% sirq
CPU9:   0% usr   0% sys   0% nic  99% idle   0% io   0% irq   0% sirq
CPU10:   0% usr   0% sys   0% nic  99% idle   0% io   0% irq   0% sirq
CPU11:   0% usr   0% sys   0% nic  99% idle   0% io   0% irq   0% sirq
Load average: 0.84 0.50 0.40 3/485 11
  PID  PPID USER     STAT   VSZ %VSZ CPU %CPU COMMAND
    6     1 root     R     6888   1%   1   8% {stress-ng-cpu} /usr/bin/stress-ng -c 1 --metrics-brief
    1     0 root     S     6244   1%  10   0% /usr/bin/stress-ng -c 1 --metrics-brief
    7     0 root     R     1504   0%  11   0% top
/<code>

19.2 qos 質量管理

• GuranteedW

<code>每個容器同時設置了 CPU 和內存的 requests 和 limits，而且
    cpu.limits = cpu.requests
    memory.limits = memory.requests
那麼它將優先被調度
/<code>

• Burstable

<code>至少有一個容器設置 CPU 或內存資源的 requests 屬性

那麼它將具有中等優先級
/<code>

• BestEffort

<code>沒有任何一個容器設置了 requests 或 limits 屬性 


那麼它將只有最低優先級，當資源不夠用的時候，這個容器可能最先被終止，以騰出資源來，為 Burstable 和 Guranteed
/<code>

• oom 策略

<code>最先殺死佔用量和需求量的比例大的
/<code>

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