/*
Copyright 2017 The Kubernetes Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package cm
import (
"fmt"
"strconv"
"strings"
"sync"
"time"
v1 "k8s.io/api/core/v1"
"k8s.io/klog/v2"
"k8s.io/apimachinery/pkg/util/wait"
units "github.com/docker/go-units"
libcontainercgroups "github.com/opencontainers/runc/libcontainer/cgroups"
utilfeature "k8s.io/apiserver/pkg/util/feature"
"k8s.io/component-helpers/resource"
v1qos "k8s.io/kubernetes/pkg/apis/core/v1/helper/qos"
kubefeatures "k8s.io/kubernetes/pkg/features"
)
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 {
Start(func() v1.ResourceList, ActivePodsFunc) error
GetQOSContainersInfo() QOSContainersInfo
UpdateCgroups() error
}
type qosContainerManagerImpl struct {
sync.Mutex
qosContainersInfo QOSContainersInfo
subsystems *CgroupSubsystems
cgroupManager CgroupManager
activePods ActivePodsFunc
getNodeAllocatable func() v1.ResourceList
cgroupRoot CgroupName
qosReserved map[v1.ResourceName]int64
}
func NewQOSContainerManager(subsystems *CgroupSubsystems, cgroupRoot CgroupName, nodeConfig NodeConfig, cgroupManager CgroupManager) (QOSContainerManager, error) {
if !nodeConfig.CgroupsPerQOS {
return &qosContainerManagerNoop{
cgroupRoot: cgroupRoot,
}, nil
}
return &qosContainerManagerImpl{
subsystems: subsystems,
cgroupManager: cgroupManager,
cgroupRoot: cgroupRoot,
qosReserved: nodeConfig.QOSReserved,
}, nil
}
func (m *qosContainerManagerImpl) GetQOSContainersInfo() QOSContainersInfo {
return m.qosContainersInfo
}
func (m *qosContainerManagerImpl) Start(getNodeAllocatable func() v1.ResourceList, activePods ActivePodsFunc) error {
cm := m.cgroupManager
rootContainer := m.cgroupRoot
if err := cm.Validate(rootContainer); err != nil {
return fmt.Errorf("error validating root container %v : %w", rootContainer, err)
}
// Top level for Qos containers are created only for Burstable
// and Best Effort classes
qosClasses := map[v1.PodQOSClass]CgroupName{
v1.PodQOSBurstable: NewCgroupName(rootContainer, strings.ToLower(string(v1.PodQOSBurstable))),
v1.PodQOSBestEffort: NewCgroupName(rootContainer, strings.ToLower(string(v1.PodQOSBestEffort))),
}
// Create containers for both qos classes
for qosClass, containerName := range qosClasses {
resourceParameters := &ResourceConfig{}
// the BestEffort QoS class has a statically configured minShares value
if qosClass == v1.PodQOSBestEffort {
minShares := uint64(MinShares)
resourceParameters.CPUShares = &minShares
}
// containerConfig object stores the cgroup specifications
containerConfig := &CgroupConfig{
Name: containerName,
ResourceParameters: resourceParameters,
}
// for each enumerated huge page size, the qos tiers are unbounded
m.setHugePagesUnbounded(containerConfig)
// check if it exists
if !cm.Exists(containerName) {
if err := cm.Create(containerConfig); err != nil {
return fmt.Errorf("failed to create top level %v QOS cgroup : %v", qosClass, err)
}
} else {
// to ensure we actually have the right state, we update the config on startup
if err := cm.Update(containerConfig); err != nil {
return fmt.Errorf("failed to update top level %v QOS cgroup : %v", qosClass, err)
}
}
}
// Store the top level qos container names
m.qosContainersInfo = QOSContainersInfo{
Guaranteed: rootContainer,
Burstable: qosClasses[v1.PodQOSBurstable],
BestEffort: qosClasses[v1.PodQOSBestEffort],
}
m.getNodeAllocatable = getNodeAllocatable
m.activePods = activePods
// update qos cgroup tiers on startup and in periodic intervals
// to ensure desired state is in sync with actual state.
go wait.Until(func() {
err := m.UpdateCgroups()
if err != nil {
klog.InfoS("Failed to reserve QoS requests", "err", err)
}
}, periodicQOSCgroupUpdateInterval, wait.NeverStop)
return nil
}
// setHugePagesUnbounded ensures hugetlb is effectively unbounded
func (m *qosContainerManagerImpl) setHugePagesUnbounded(cgroupConfig *CgroupConfig) error {
hugePageLimit := map[int64]int64{}
for _, pageSize := range libcontainercgroups.HugePageSizes() {
pageSizeBytes, err := units.RAMInBytes(pageSize)
if err != nil {
return err
}
hugePageLimit[pageSizeBytes] = int64(1 << 62)
}
cgroupConfig.ResourceParameters.HugePageLimit = hugePageLimit
return nil
}
func (m *qosContainerManagerImpl) setHugePagesConfig(configs map[v1.PodQOSClass]*CgroupConfig) error {
for _, v := range configs {
if err := m.setHugePagesUnbounded(v); err != nil {
return err
}
}
return nil
}
func (m *qosContainerManagerImpl) setCPUCgroupConfig(configs map[v1.PodQOSClass]*CgroupConfig) error {
pods := m.activePods()
burstablePodCPURequest := int64(0)
reuseReqs := make(v1.ResourceList, 4)
for i := range pods {
pod := pods[i]
qosClass := v1qos.GetPodQOS(pod)
if qosClass != v1.PodQOSBurstable {
// we only care about the burstable qos tier
continue
}
req := resource.PodRequests(pod, resource.PodResourcesOptions{Reuse: reuseReqs})
if request, found := req[v1.ResourceCPU]; found {
burstablePodCPURequest += request.MilliValue()
}
}
// make sure best effort is always 2 shares
bestEffortCPUShares := uint64(MinShares)
configs[v1.PodQOSBestEffort].ResourceParameters.CPUShares = &bestEffortCPUShares
// set burstable shares based on current observe state
burstableCPUShares := MilliCPUToShares(burstablePodCPURequest)
configs[v1.PodQOSBurstable].ResourceParameters.CPUShares = &burstableCPUShares
return nil
}
// getQoSMemoryRequests sums and returns the memory request of all pods for
// guaranteed and burstable qos classes.
func (m *qosContainerManagerImpl) getQoSMemoryRequests() map[v1.PodQOSClass]int64 {
qosMemoryRequests := map[v1.PodQOSClass]int64{
v1.PodQOSGuaranteed: 0,
v1.PodQOSBurstable: 0,
}
// Sum the pod limits for pods in each QOS class
pods := m.activePods()
reuseReqs := make(v1.ResourceList, 4)
for _, pod := range pods {
podMemoryRequest := int64(0)
qosClass := v1qos.GetPodQOS(pod)
if qosClass == v1.PodQOSBestEffort {
// limits are not set for Best Effort pods
continue
}
req := resource.PodRequests(pod, resource.PodResourcesOptions{Reuse: reuseReqs})
if request, found := req[v1.ResourceMemory]; found {
podMemoryRequest += request.Value()
}
qosMemoryRequests[qosClass] += podMemoryRequest
}
return qosMemoryRequests
}
// setMemoryReserve sums the memory limits of all pods in a QOS class,
// calculates QOS class memory limits, and set those limits in the
// CgroupConfig for each QOS class.
func (m *qosContainerManagerImpl) setMemoryReserve(configs map[v1.PodQOSClass]*CgroupConfig, percentReserve int64) {
qosMemoryRequests := m.getQoSMemoryRequests()
resources := m.getNodeAllocatable()
allocatableResource, ok := resources[v1.ResourceMemory]
if !ok {
klog.V(2).InfoS("Allocatable memory value could not be determined, not setting QoS memory limits")
return
}
allocatable := allocatableResource.Value()
if allocatable == 0 {
klog.V(2).InfoS("Allocatable memory reported as 0, might be in standalone mode, not setting QoS memory limits")
return
}
for qos, limits := range qosMemoryRequests {
klog.V(2).InfoS("QoS pod memory limit", "qos", qos, "limits", limits, "percentReserve", percentReserve)
}
// Calculate QOS memory limits
burstableLimit := allocatable - (qosMemoryRequests[v1.PodQOSGuaranteed] * percentReserve / 100)
bestEffortLimit := burstableLimit - (qosMemoryRequests[v1.PodQOSBurstable] * percentReserve / 100)
configs[v1.PodQOSBurstable].ResourceParameters.Memory = &burstableLimit
configs[v1.PodQOSBestEffort].ResourceParameters.Memory = &bestEffortLimit
}
// retrySetMemoryReserve checks for any QoS cgroups over the limit
// that was attempted to be set in the first Update() and adjusts
// their memory limit to the usage to prevent further growth.
func (m *qosContainerManagerImpl) retrySetMemoryReserve(configs map[v1.PodQOSClass]*CgroupConfig, percentReserve int64) {
// Unreclaimable memory usage may already exceeded the desired limit
// Attempt to set the limit near the current usage to put pressure
// on the cgroup and prevent further growth.
for qos, config := range configs {
usage, err := m.cgroupManager.MemoryUsage(config.Name)
if err != nil {
klog.V(2).InfoS("Failed to get resource stats", "err", err)
return
}
// Because there is no good way to determine of the original Update()
// on the memory resource was successful, we determine failure of the
// first attempt by checking if the usage is above the limit we attempt
// to set. If it is, we assume the first attempt to set the limit failed
// and try again setting the limit to the usage. Otherwise we leave
// the CgroupConfig as is.
if configs[qos].ResourceParameters.Memory != nil && usage > *configs[qos].ResourceParameters.Memory {
configs[qos].ResourceParameters.Memory = &usage
}
}
}
// setMemoryQoS sums the memory requests of all pods in the Burstable class,
// and set the sum memory as the memory.min in the Unified field of CgroupConfig.
func (m *qosContainerManagerImpl) setMemoryQoS(configs map[v1.PodQOSClass]*CgroupConfig) {
qosMemoryRequests := m.getQoSMemoryRequests()
// Calculate the memory.min:
// for burstable(/kubepods/burstable): sum of all burstable pods
// for guaranteed(/kubepods): sum of all guaranteed and burstable pods
burstableMin := qosMemoryRequests[v1.PodQOSBurstable]
guaranteedMin := qosMemoryRequests[v1.PodQOSGuaranteed] + burstableMin
if burstableMin > 0 {
if configs[v1.PodQOSBurstable].ResourceParameters.Unified == nil {
configs[v1.PodQOSBurstable].ResourceParameters.Unified = make(map[string]string)
}
configs[v1.PodQOSBurstable].ResourceParameters.Unified[Cgroup2MemoryMin] = strconv.FormatInt(burstableMin, 10)
klog.V(4).InfoS("MemoryQoS config for qos", "qos", v1.PodQOSBurstable, "memoryMin", burstableMin)
}
if guaranteedMin > 0 {
if configs[v1.PodQOSGuaranteed].ResourceParameters.Unified == nil {
configs[v1.PodQOSGuaranteed].ResourceParameters.Unified = make(map[string]string)
}
configs[v1.PodQOSGuaranteed].ResourceParameters.Unified[Cgroup2MemoryMin] = strconv.FormatInt(guaranteedMin, 10)
klog.V(4).InfoS("MemoryQoS config for qos", "qos", v1.PodQOSGuaranteed, "memoryMin", guaranteedMin)
}
}
func (m *qosContainerManagerImpl) UpdateCgroups() error {
m.Lock()
defer m.Unlock()
qosConfigs := map[v1.PodQOSClass]*CgroupConfig{
v1.PodQOSGuaranteed: {
Name: m.qosContainersInfo.Guaranteed,
ResourceParameters: &ResourceConfig{},
},
v1.PodQOSBurstable: {
Name: m.qosContainersInfo.Burstable,
ResourceParameters: &ResourceConfig{},
},
v1.PodQOSBestEffort: {
Name: m.qosContainersInfo.BestEffort,
ResourceParameters: &ResourceConfig{},
},
}
// update the qos level cgroup settings for cpu shares
if err := m.setCPUCgroupConfig(qosConfigs); err != nil {
return err
}
// update the qos level cgroup settings for huge pages (ensure they remain unbounded)
if err := m.setHugePagesConfig(qosConfigs); err != nil {
return err
}
// update the qos level cgrougs v2 settings of memory qos if feature enabled
if utilfeature.DefaultFeatureGate.Enabled(kubefeatures.MemoryQoS) &&
libcontainercgroups.IsCgroup2UnifiedMode() {
m.setMemoryQoS(qosConfigs)
}
if utilfeature.DefaultFeatureGate.Enabled(kubefeatures.QOSReserved) {
for resource, percentReserve := range m.qosReserved {
switch resource {
case v1.ResourceMemory:
m.setMemoryReserve(qosConfigs, percentReserve)
}
}
updateSuccess := true
for _, config := range qosConfigs {
err := m.cgroupManager.Update(config)
if err != nil {
updateSuccess = false
}
}
if updateSuccess {
klog.V(4).InfoS("Updated QoS cgroup configuration")
return nil
}
// If the resource can adjust the ResourceConfig to increase likelihood of
// success, call the adjustment function here. Otherwise, the Update() will
// be called again with the same values.
for resource, percentReserve := range m.qosReserved {
switch resource {
case v1.ResourceMemory:
m.retrySetMemoryReserve(qosConfigs, percentReserve)
}
}
}
for _, config := range qosConfigs {
err := m.cgroupManager.Update(config)
if err != nil {
klog.ErrorS(err, "Failed to update QoS cgroup configuration")
return err
}
}
klog.V(4).InfoS("Updated QoS cgroup configuration")
return nil
}
type qosContainerManagerNoop struct {
cgroupRoot CgroupName
}
var _ QOSContainerManager = &qosContainerManagerNoop{}
func (m *qosContainerManagerNoop) GetQOSContainersInfo() QOSContainersInfo {
return QOSContainersInfo{}
}
func (m *qosContainerManagerNoop) Start(_ func() v1.ResourceList, _ ActivePodsFunc) error {
return nil
}
func (m *qosContainerManagerNoop) UpdateCgroups() error {
return nil
}
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