Enable kernel memcg notification via additional flag

cmd/kubelet/app/options/options.go

@@ -249,6 +249,7 @@ func (s *KubeletServer) AddFlags(fs *pflag.FlagSet) {
 	fs.DurationVar(&s.EvictionPressureTransitionPeriod.Duration, "eviction-pressure-transition-period", s.EvictionPressureTransitionPeriod.Duration, "Duration for which the kubelet has to wait before transitioning out of an eviction pressure condition.")
 	fs.Int32Var(&s.EvictionMaxPodGracePeriod, "eviction-max-pod-grace-period", s.EvictionMaxPodGracePeriod, "Maximum allowed grace period (in seconds) to use when terminating pods in response to a soft eviction threshold being met.  If negative, defer to pod specified value.")
 	fs.StringVar(&s.EvictionMinimumReclaim, "eviction-minimum-reclaim", s.EvictionMinimumReclaim, "A set of minimum reclaims (e.g. imagefs.available=2Gi) that describes the minimum amount of resource the kubelet will reclaim when performing a pod eviction if that resource is under pressure.")
+	fs.BoolVar(&s.ExperimentalKernelMemcgNotification, "experimental-kernel-memcg-notification", s.ExperimentalKernelMemcgNotification, "If enabled, the kubelet will integrate with the kernel memcg notification to determine if memory eviction thresholds are crossed rather than polling.")
 	fs.Int32Var(&s.PodsPerCore, "pods-per-core", s.PodsPerCore, "Number of Pods per core that can run on this Kubelet. The total number of Pods on this Kubelet cannot exceed max-pods, so max-pods will be used if this calculation results in a larger number of Pods allowed on the Kubelet. A value of 0 disables this limit.")
 	fs.BoolVar(&s.ProtectKernelDefaults, "protect-kernel-defaults", s.ProtectKernelDefaults, "Default kubelet behaviour for kernel tuning. If set, kubelet errors if any of kernel tunables is different than kubelet defaults.")
 

hack/verify-flags/known-flags.txt

@@ -202,6 +202,7 @@ experimental-nvidia-gpus
 experimental-prefix
 experimental-cri
 experimental-check-node-capabilities-before-mount
+experimental-kernel-memcg-notification
 external-etcd-cafile
 external-etcd-certfile
 external-etcd-endpoints

pkg/apis/componentconfig/types.go

@@ -430,6 +430,9 @@ type KubeletConfiguration struct {
 	// Comma-delimited list of minimum reclaims (e.g. imagefs.available=2Gi) that describes the minimum amount of resource the kubelet will reclaim when performing a pod eviction if that resource is under pressure.
 	// +optional
 	EvictionMinimumReclaim string `json:"evictionMinimumReclaim,omitempty"`
+	// If enabled, the kubelet will integrate with the kernel memcg notification to determine if memory eviction thresholds are crossed rather than polling.
+	// +optional
+	ExperimentalKernelMemcgNotification bool `json:"experimentalKernelMemcgNotification"`
 	// Maximum number of pods per core. Cannot exceed MaxPods
 	PodsPerCore int32 `json:"podsPerCore"`
 	// enableControllerAttachDetach enables the Attach/Detach controller to

pkg/apis/componentconfig/v1alpha1/defaults.go

@@ -374,6 +374,9 @@ func SetDefaults_KubeletConfiguration(obj *KubeletConfiguration) {
 	if obj.EvictionPressureTransitionPeriod == zeroDuration {
 		obj.EvictionPressureTransitionPeriod = metav1.Duration{Duration: 5 * time.Minute}
 	}
+	if obj.ExperimentalKernelMemcgNotification == nil {
+		obj.ExperimentalKernelMemcgNotification = boolVar(false)
+	}
 	if obj.SystemReserved == nil {
 		obj.SystemReserved = make(map[string]string)
 	}

pkg/apis/componentconfig/v1alpha1/types.go

@@ -472,6 +472,8 @@ type KubeletConfiguration struct {
 	EvictionMaxPodGracePeriod int32 `json:"evictionMaxPodGracePeriod"`
 	// Comma-delimited list of minimum reclaims (e.g. imagefs.available=2Gi) that describes the minimum amount of resource the kubelet will reclaim when performing a pod eviction if that resource is under pressure.
 	EvictionMinimumReclaim string `json:"evictionMinimumReclaim"`
+	// If enabled, the kubelet will integrate with the kernel memcg notification to determine if memory eviction thresholds are crossed rather than polling.
+	ExperimentalKernelMemcgNotification *bool `json:"experimentalKernelMemcgNotification"`
 	// Maximum number of pods per core. Cannot exceed MaxPods
 	PodsPerCore int32 `json:"podsPerCore"`
 	// enableControllerAttachDetach enables the Attach/Detach controller to

pkg/kubelet/eviction/eviction_manager.go

@@ -204,7 +204,8 @@ func (m *managerImpl) synchronize(diskInfoProvider DiskInfoProvider, podFunc Act
 	}
 
 	// attempt to create a threshold notifier to improve eviction response time
-	if !m.notifiersInitialized {
+	if m.config.KernelMemcgNotification && !m.notifiersInitialized {
+		glog.Infof("eviction manager attempting to integrate with kernel memcg notification api")
 		m.notifiersInitialized = true
 		// start soft memory notification
 		err = startMemoryThresholdNotifier(m.config.Thresholds, observations, false, func(desc string) {

pkg/kubelet/eviction/types.go

@@ -69,6 +69,8 @@ type Config struct {
 	MaxPodGracePeriodSeconds int64
 	// Thresholds define the set of conditions monitored to trigger eviction.
 	Thresholds []Threshold
+	// KernelMemcgNotification if true will integrate with the kernel memcg notification to determine if memory thresholds are crossed.
+	KernelMemcgNotification bool
 }
 
 // ThresholdValue is a value holder that abstracts literal versus percentage based quantity

pkg/kubelet/kubelet.go

@@ -354,6 +354,7 @@ func NewMainKubelet(kubeCfg *componentconfig.KubeletConfiguration, kubeDeps *Kub
 		PressureTransitionPeriod: kubeCfg.EvictionPressureTransitionPeriod.Duration,
 		MaxPodGracePeriodSeconds: int64(kubeCfg.EvictionMaxPodGracePeriod),
 		Thresholds:               thresholds,
+		KernelMemcgNotification:  kubeCfg.ExperimentalKernelMemcgNotification,
 	}
 
 	reservation, err := ParseReservation(kubeCfg.KubeReserved, kubeCfg.SystemReserved)