feature: support memory qos for cgroup v2

Map container.requests.memory to memory.min on cgroup v2.
See kubernetes/enhancements#2571

pkg/kubelet/cm/cgroup_manager_linux.go

@@ -51,6 +51,8 @@ const (
 	libcontainerSystemd libcontainerCgroupManagerType = "systemd"
 	// systemdSuffix is the cgroup name suffix for systemd
 	systemdSuffix string = ".slice"
+	// MemoryMin is memory.min for cgroup v2
+	MemoryMin string = "memory.min"
 )
 
 var RootCgroupName = CgroupName([]string{})

pkg/kubelet/kuberuntime/kuberuntime_container_linux.go

@@ -19,6 +19,7 @@ limitations under the License.
 package kuberuntime
 
 import (
+	"strconv"
 	"time"
 
 	cgroupfs "github.com/opencontainers/runc/libcontainer/cgroups/fs"
@@ -28,6 +29,7 @@ import (
 	"k8s.io/klog/v2"
 	v1helper "k8s.io/kubernetes/pkg/apis/core/v1/helper"
 	kubefeatures "k8s.io/kubernetes/pkg/features"
+	"k8s.io/kubernetes/pkg/kubelet/cm"
 	kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
 	"k8s.io/kubernetes/pkg/kubelet/qos"
 )
@@ -55,6 +57,7 @@ func (m *kubeGenericRuntimeManager) generateLinuxContainerConfig(container *v1.C
 	cpuRequest := container.Resources.Requests.Cpu()
 	cpuLimit := container.Resources.Limits.Cpu()
 	memoryLimit := container.Resources.Limits.Memory().Value()
+	memoryRequest := container.Resources.Requests.Memory().Value()
 	oomScoreAdj := int64(qos.GetContainerOOMScoreAdjust(pod, container,
 		int64(m.machineInfo.MemoryCapacity)))
 	// If request is not specified, but limit is, we want request to default to limit.
@@ -71,6 +74,12 @@ func (m *kubeGenericRuntimeManager) generateLinuxContainerConfig(container *v1.C
 	if memoryLimit != 0 {
 		lc.Resources.MemoryLimitInBytes = memoryLimit
 	}
+	if memoryRequest != 0 {
+		if lc.Resources.Unified == nil {
+			lc.Resources.Unified = make(map[string]string)
+		}
+		lc.Resources.Unified[cm.MemoryMin] = strconv.FormatInt(memoryRequest, 10)
+	}
 	// Set OOM score of the container based on qos policy. Processes in lower-priority pods should
 	// be killed first if the system runs out of memory.
 	lc.Resources.OomScoreAdj = oomScoreAdj