简单总结

1.32前cpumanager对于非guaranteed或者request非整数,则仍然会使用reservedCPUs
1.32后新增了strict-cpu-reservation option,设置为true后,pod无法使用reservedCPUs

源码

pkg/kubelet/cm/cpumanager/cpu_manager.go中

构建cpumanager
func NewManager(cpuPolicyName string, cpuPolicyOptions map[string]string, reconcilePeriod time.Duration, machineInfo *cadvisorapi.MachineInfo, specificCPUs cpuset.CPUSet, nodeAllocatableReservation v1.ResourceList, stateFileDirectory string, affinity topologymanager.Store) (Manager, error) {
    ...
    switch policyName(cpuPolicyName) {
    ...
    case PolicyStatic:
        ...
        policy, err = NewStaticPolicy(topo, numReservedCPUs, specificCPUs, affinity, cpuPolicyOptions)
        ...
    ...
    return manager, nil
}

启动
func (m *manager) Start(activePods ActivePodsFunc, sourcesReady config.SourcesReady, podStatusProvider status.PodStatusProvider, containerRuntime runtimeService, initialContainers containermap.ContainerMap) error {
    ...
    加载checkpoint
    stateImpl, err := state.NewCheckpointState(m.stateFileDirectory, cpuManagerStateFileName, m.policy.Name(), m.containerMap)
    if err != nil {
        return err
    }
    m.state = stateImpl
    启动policy
    err = m.policy.Start(m.state)
    if err != nil {
        return err
    }
}

pkg/kubelet/cm/cpumanager/policy_static.go中

构建policy
func NewStaticPolicy(topology *topology.CPUTopology, numReservedCPUs int, reservedCPUs cpuset.CPUSet, affinity topologymanager.Store, cpuPolicyOptions map[string]string) (Policy, error) {
    ...
    return policy, nil
}


启动
func (p *staticPolicy) Start(s state.State) error {
    校验状态
    if err := p.validateState(s); err != nil {
    }
    return nil
}

校验状态
func (p *staticPolicy) validateState(s state.State) error {
    ...
    tmpDefaultCPUset := s.GetDefaultCPUSet()

    allCPUs := p.topology.CPUDetails.CPUs()
    如果开启了strict-cpu-reservation，那么reservedCPUs不能包含在allCPUs中
    1.32前没有这三行
    if p.options.StrictCPUReservation {
        allCPUs = allCPUs.Difference(p.reservedCPUs)
    }
    如果checkpoint中没有defaultCPUset
    if tmpDefaultCPUset.IsEmpty() {
        ...
        设置state中的defaultCPUset为allCPUs(已移除reservedCPUs)
        s.SetDefaultCPUSet(allCPUs)
        return nil
    }
}

获取可用的cpu
func (p *staticPolicy) GetAvailableCPUs(s state.State) cpuset.CPUSet {
    默认cpu去除reservedCPUs
    return s.GetDefaultCPUSet().Difference(p.reservedCPUs)
}

分配cpu
func (p *staticPolicy) Allocate(s state.State, pod *v1.Pod, container *v1.Container) (rerr error) {
    numCPUs := p.guaranteedCPUs(pod, container)
    if numCPUs == 0 {
        使用defaultCPUset(即上面移除了reservedCPUs的cpu)
        return nil
    }
    ...
}