Merge pull request #41753 from derekwaynecarr/burstable-cpu-shares

Automatic merge from submit-queue (batch tested with PRs 41644, 42020, 41753, 42206, 42212)

Burstable QoS cgroup has cpu shares assigned

**What this PR does / why we need it**:
This PR sets the Burstable QoS cgroup cpu shares value to the sum of the pods cpu requests in that tier.  We need it for proper evaluation of CPU shares in the new QoS hierarchy.

**Special notes for your reviewer**:
It builds against the framework proposed for https://github.com/kubernetes/kubernetes/pull/41833

pkg/kubelet/cm/qos_container_manager_linux.go

@@ -20,8 +20,20 @@ import (
 	"fmt"
 	"path"
 	"sync"
+	"time"
+
+	"github.com/golang/glog"
+
+	"k8s.io/apimachinery/pkg/util/wait"
 
 	"k8s.io/kubernetes/pkg/api/v1"
+	"k8s.io/kubernetes/pkg/kubelet/qos"
+)
+
+const (
+	// how often the qos cgroup manager will perform periodic update
+	// of the qos level cgroup resource constraints
+	periodicQOSCgroupUpdateInterval = 1 * time.Minute
 )
 
 type QOSContainerManager interface {
@@ -106,6 +118,47 @@ func (m *qosContainerManagerImpl) Start(nodeInfo *v1.Node, activePods ActivePods
 	m.nodeInfo = nodeInfo
 	m.activePods = activePods
 
+	// update qos cgroup tiers on startup and in periodic intervals
+	// to ensure desired state is in synch with actual state.
+	go wait.Until(func() {
+		err := m.UpdateCgroups()
+		if err != nil {
+			glog.Warningf("[ContainerManager] Failed to reserve QoS requests: %v", err)
+		}
+	}, periodicQOSCgroupUpdateInterval, wait.NeverStop)
+
+	return nil
+}
+
+func (m *qosContainerManagerImpl) setCPUCgroupConfig(configs map[v1.PodQOSClass]*CgroupConfig) error {
+	pods := m.activePods()
+	burstablePodCPURequest := int64(0)
+	for i := range pods {
+		pod := pods[i]
+		qosClass := qos.GetPodQOS(pod)
+		if qosClass != v1.PodQOSBurstable {
+			// we only care about the burstable qos tier
+			continue
+		}
+		req, _, err := v1.PodRequestsAndLimits(pod)
+		if err != nil {
+			return err
+		}
+		if request, found := req[v1.ResourceCPU]; found {
+			burstablePodCPURequest += request.MilliValue()
+		}
+	}
+
+	// make sure best effort is always 2 shares
+	bestEffortCPUShares := int64(MinShares)
+	configs[v1.PodQOSBestEffort].ResourceParameters.CpuShares = &bestEffortCPUShares
+
+	// set burstable shares based on current observe state
+	burstableCPUShares := MilliCPUToShares(burstablePodCPURequest)
+	if burstableCPUShares < int64(MinShares) {
+		burstableCPUShares = int64(MinShares)
+	}
+	configs[v1.PodQOSBurstable].ResourceParameters.CpuShares = &burstableCPUShares
 	return nil
 }
 
@@ -113,7 +166,30 @@ func (m *qosContainerManagerImpl) UpdateCgroups() error {
 	m.Lock()
 	defer m.Unlock()
 
-	// TODO: Update cgroups
+	qosConfigs := map[v1.PodQOSClass]*CgroupConfig{
+		v1.PodQOSBurstable: {
+			Name:               CgroupName(m.qosContainersInfo.Burstable),
+			ResourceParameters: &ResourceConfig{},
+		},
+		v1.PodQOSBestEffort: {
+			Name:               CgroupName(m.qosContainersInfo.BestEffort),
+			ResourceParameters: &ResourceConfig{},
+		},
+	}
+
+	// update the qos level cgroup settings for cpu shares
+	if err := m.setCPUCgroupConfig(qosConfigs); err != nil {
+		return err
+	}
+
+	for _, config := range qosConfigs {
+		err := m.cgroupManager.Update(config)
+		if err != nil {
+			glog.V(2).Infof("[ContainerManager]: Failed to update QoS cgroup configuration")
+			return err
+		}
+	}
+	glog.V(2).Infof("[ContainerManager]: Updated QoS cgroup configuration")
 
 	return nil
 }