ClusterAutoscaler: first fit decreasing estimate algorithm
This commit is contained in:
Marcin Wielgus
parent
771c92e989
commit
0561d0ea84
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/*
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Copyright 2016 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package estimator
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import (
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"sort"
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"k8s.io/contrib/cluster-autoscaler/simulator"
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kube_api "k8s.io/kubernetes/pkg/api"
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"k8s.io/kubernetes/pkg/api/resource"
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"k8s.io/kubernetes/plugin/pkg/scheduler/schedulercache"
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)
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// podInfo contains Pod and score that corresponds to how important it is to handle the pod first.
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type podInfo struct {
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score float64
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pod *kube_api.Pod
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}
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type byScoreDesc []*podInfo
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func (a byScoreDesc) Len() int { return len(a) }
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func (a byScoreDesc) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
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func (a byScoreDesc) Less(i, j int) bool { return a[i].score > a[j].score }
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// BinpackingNodeEstimator estimates the number of needed nodes to handle the given amount of pods.
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type BinpackingNodeEstimator struct {
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predicateChecker *simulator.PredicateChecker
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}
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// NewBinpackingNodeEstimator builds a new BinpackingNodeEstimator.
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func NewBinpackingNodeEstimator(predicateChecker *simulator.PredicateChecker) *BinpackingNodeEstimator {
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return &BinpackingNodeEstimator{
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predicateChecker: predicateChecker,
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}
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}
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// Estimate implements First Fit Decreasing bin-packing approximation algorithm.
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// See https://en.wikipedia.org/wiki/Bin_packing_problem for more details.
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// While it is a multi-dimensional bin packing (cpu, mem, ports) in most cases the main dimension
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// will be cpu thus the estimated overprovisioning of 11/9 * optimal + 6/9 should be
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// still be maintained.
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// It is assumed that all pods from the given list can fit to nodeTemplate.
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// Returns the number of nodes needed to accommodate all pods from the list.
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func (estimator *BinpackingNodeEstimator) Estimate(pods []*kube_api.Pod, nodeTemplate *schedulercache.NodeInfo) int {
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podInfos := calculatePodScore(pods, nodeTemplate)
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sort.Sort(byScoreDesc(podInfos))
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// nodeWithPod function returns NodeInfo, which is a copy of nodeInfo argument with an additional pod scheduled on it.
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nodeWithPod := func(nodeInfo *schedulercache.NodeInfo, pod *kube_api.Pod) *schedulercache.NodeInfo {
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podsOnNode := nodeInfo.Pods()
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podsOnNode = append(podsOnNode, pod)
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newNodeInfo := schedulercache.NewNodeInfo(podsOnNode...)
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newNodeInfo.SetNode(nodeInfo.Node())
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return newNodeInfo
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}
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newNodes := make([]*schedulercache.NodeInfo, 0)
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for _, podInfo := range podInfos {
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found := false
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for i, nodeInfo := range newNodes {
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if err := estimator.predicateChecker.CheckPredicates(podInfo.pod, nodeInfo); err == nil {
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found = true
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newNodes[i] = nodeWithPod(nodeInfo, podInfo.pod)
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break
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}
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}
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if !found {
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newNodes = append(newNodes, nodeWithPod(nodeTemplate, podInfo.pod))
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}
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}
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return len(newNodes)
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}
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// Calculates score for all pods and returns podInfo structure.
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// Score is defined as cpu_sum/node_capacity + mem_sum/node_capacity.
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// Pods that have bigger requirements should be processed first, thus have higher scores.
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func calculatePodScore(pods []*kube_api.Pod, nodeTemplate *schedulercache.NodeInfo) []*podInfo {
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podInfos := make([]*podInfo, 0, len(pods))
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for _, pod := range pods {
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cpuSum := resource.Quantity{}
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memorySum := resource.Quantity{}
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for _, container := range pod.Spec.Containers {
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if request, ok := container.Resources.Requests[kube_api.ResourceCPU]; ok {
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cpuSum.Add(request)
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}
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if request, ok := container.Resources.Requests[kube_api.ResourceMemory]; ok {
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memorySum.Add(request)
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}
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}
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score := float64(0)
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if cpuAllocatable, ok := nodeTemplate.Node().Status.Allocatable[kube_api.ResourceCPU]; ok && cpuAllocatable.MilliValue() > 0 {
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score += float64(cpuSum.MilliValue()) / float64(cpuAllocatable.MilliValue())
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}
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if memAllocatable, ok := nodeTemplate.Node().Status.Allocatable[kube_api.ResourceMemory]; ok && memAllocatable.Value() > 0 {
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score += float64(memorySum.Value()) / float64(memAllocatable.Value())
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}
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podInfos = append(podInfos, &podInfo{
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score: score,
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pod: pod,
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})
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}
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return podInfos
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}
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@ -0,0 +1,114 @@
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/*
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Copyright 2016 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package estimator
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import (
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"testing"
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"k8s.io/contrib/cluster-autoscaler/simulator"
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kube_api "k8s.io/kubernetes/pkg/api"
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"k8s.io/kubernetes/pkg/api/resource"
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"k8s.io/kubernetes/plugin/pkg/scheduler/schedulercache"
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"github.com/stretchr/testify/assert"
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)
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func TestBinpackingEstimate(t *testing.T) {
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estimator := NewBinpackingNodeEstimator(simulator.NewTestPredicateChecker())
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cpuPerPod := int64(350)
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memoryPerPod := int64(1000 * 1024 * 1024)
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pod := &kube_api.Pod{
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Spec: kube_api.PodSpec{
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Containers: []kube_api.Container{
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{
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Resources: kube_api.ResourceRequirements{
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Requests: kube_api.ResourceList{
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kube_api.ResourceCPU: *resource.NewMilliQuantity(cpuPerPod, resource.DecimalSI),
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kube_api.ResourceMemory: *resource.NewQuantity(memoryPerPod, resource.DecimalSI),
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},
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},
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},
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},
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},
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}
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pods := make([]*kube_api.Pod, 0)
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for i := 0; i < 10; i++ {
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pods = append(pods, pod)
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}
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node := &kube_api.Node{
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Status: kube_api.NodeStatus{
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Capacity: kube_api.ResourceList{
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kube_api.ResourceCPU: *resource.NewMilliQuantity(cpuPerPod*3-50, resource.DecimalSI),
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kube_api.ResourceMemory: *resource.NewQuantity(2*memoryPerPod, resource.DecimalSI),
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kube_api.ResourcePods: *resource.NewQuantity(10, resource.DecimalSI),
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},
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},
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}
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node.Status.Allocatable = node.Status.Capacity
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nodeInfo := schedulercache.NewNodeInfo()
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nodeInfo.SetNode(node)
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estimate := estimator.Estimate(pods, nodeInfo)
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assert.Equal(t, 5, estimate)
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}
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func TestBinpackingEstimateWithPorts(t *testing.T) {
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estimator := NewBinpackingNodeEstimator(simulator.NewTestPredicateChecker())
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cpuPerPod := int64(200)
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memoryPerPod := int64(1000 * 1024 * 1024)
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pod := &kube_api.Pod{
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Spec: kube_api.PodSpec{
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Containers: []kube_api.Container{
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{
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Resources: kube_api.ResourceRequirements{
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Requests: kube_api.ResourceList{
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kube_api.ResourceCPU: *resource.NewMilliQuantity(cpuPerPod, resource.DecimalSI),
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kube_api.ResourceMemory: *resource.NewQuantity(memoryPerPod, resource.DecimalSI),
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},
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},
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Ports: []kube_api.ContainerPort{
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{
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HostPort: 5555,
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},
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},
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},
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},
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},
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}
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pods := make([]*kube_api.Pod, 0)
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for i := 0; i < 8; i++ {
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pods = append(pods, pod)
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}
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node := &kube_api.Node{
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Status: kube_api.NodeStatus{
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Capacity: kube_api.ResourceList{
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kube_api.ResourceCPU: *resource.NewMilliQuantity(5*cpuPerPod, resource.DecimalSI),
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kube_api.ResourceMemory: *resource.NewQuantity(5*memoryPerPod, resource.DecimalSI),
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kube_api.ResourcePods: *resource.NewQuantity(10, resource.DecimalSI),
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},
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},
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}
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node.Status.Allocatable = node.Status.Capacity
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nodeInfo := schedulercache.NewNodeInfo()
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nodeInfo.SetNode(node)
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estimate := estimator.Estimate(pods, nodeInfo)
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assert.Equal(t, 8, estimate)
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}
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