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Merge pull request #30274 from mwielgus/best-fit 

Automatic merge from submit-queue

ClusterAutoscaler-friendly scheduler priority function that promotes well-used nodes

It will help cluster autoscaler to put pods on nodes that are unlikely to be deleted soon due to low usage. Otherwise a pod may be frequently kicked from one node to another. A flag that enables it when CA is on will be added in a separate PR.

Fixes: #28842
pull/6/head
Kubernetes Submit Queue 2016-08-18 23:49:09 -07:00 committed by GitHub
parent b1194ffb43 de2fea95ca
commit 1f3a703df1
3 changed files with 228 additions and 8 deletions
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79
plugin/pkg/scheduler/algorithm/priorities/priorities.go
View File

@ -39,9 +39,10 @@ func getNonZeroRequests(pod *api.Pod) *schedulercache.Resource {
return result
}
// the unused capacity is calculated on a scale of 0-10
// 0 being the lowest priority and 10 being the highest
func calculateScore(requested int64, capacity int64, node string) int64 {
// The unused capacity is calculated on a scale of 0-10
// 0 being the lowest priority and 10 being the highest.
// The more unused resources the higher the score is.
func calculateUnusedScore(requested int64, capacity int64, node string) int64 {
if capacity == 0 {
return 0
}
@ -53,17 +54,37 @@ func calculateScore(requested int64, capacity int64, node string) int64 {
return ((capacity - requested) * 10) / capacity
}
// Calculate the resource occupancy on a node. 'node' has information about the resources on the node.
// The used capacity is calculated on a scale of 0-10
// 0 being the lowest priority and 10 being the highest.
// The more resources are used the higher the score is. This function
// is almost a reversed version of calculatUnusedScore (10 - calculateUnusedScore).
// The main difference is in rounding. It was added to keep the
// final formula clean and not to modify the widely used (by users
// in their default scheduling policies) calculateUSedScore.
func calculateUsedScore(requested int64, capacity int64, node string) int64 {
if capacity == 0 {
return 0
}
if requested > capacity {
glog.V(2).Infof("Combined requested resources %d from existing pods exceeds capacity %d on node %s",
requested, capacity, node)
return 0
}
return (requested * 10) / capacity
}
// Calculates host priority based on the amount of unused resources.
// 'node' has information about the resources on the node.
// 'pods' is a list of pods currently scheduled on the node.
// TODO: Use Node() from nodeInfo instead of passing it.
func calculateResourceOccupancy(pod *api.Pod, podRequests *schedulercache.Resource, node *api.Node, nodeInfo *schedulercache.NodeInfo) schedulerapi.HostPriority {
func calculateUnusedPriority(pod *api.Pod, podRequests *schedulercache.Resource, node *api.Node, nodeInfo *schedulercache.NodeInfo) schedulerapi.HostPriority {
allocatableResources := nodeInfo.AllocatableResource()
totalResources := *podRequests
totalResources.MilliCPU += nodeInfo.NonZeroRequest().MilliCPU
totalResources.Memory += nodeInfo.NonZeroRequest().Memory
cpuScore := calculateScore(totalResources.MilliCPU, allocatableResources.MilliCPU, node.Name)
memoryScore := calculateScore(totalResources.Memory, allocatableResources.Memory, node.Name)
cpuScore := calculateUnusedScore(totalResources.MilliCPU, allocatableResources.MilliCPU, node.Name)
memoryScore := calculateUnusedScore(totalResources.Memory, allocatableResources.Memory, node.Name)
if glog.V(10) {
// We explicitly don't do glog.V(10).Infof() to avoid computing all the parameters if this is
// not logged. There is visible performance gain from it.
@ -82,6 +103,35 @@ func calculateResourceOccupancy(pod *api.Pod, podRequests *schedulercache.Resour
}
}
// Calculate the resource used on a node. 'node' has information about the resources on the node.
// 'pods' is a list of pods currently scheduled on the node.
// TODO: Use Node() from nodeInfo instead of passing it.
func calculateUsedPriority(pod *api.Pod, podRequests *schedulercache.Resource, node *api.Node, nodeInfo *schedulercache.NodeInfo) schedulerapi.HostPriority {
allocatableResources := nodeInfo.AllocatableResource()
totalResources := *podRequests
totalResources.MilliCPU += nodeInfo.NonZeroRequest().MilliCPU
totalResources.Memory += nodeInfo.NonZeroRequest().Memory
cpuScore := calculateUsedScore(totalResources.MilliCPU, allocatableResources.MilliCPU, node.Name)
memoryScore := calculateUsedScore(totalResources.Memory, allocatableResources.Memory, node.Name)
if glog.V(10) {
// We explicitly don't do glog.V(10).Infof() to avoid computing all the parameters if this is
// not logged. There is visible performance gain from it.
glog.V(10).Infof(
"%v -> %v: Most Requested Priority, capacity %d millicores %d memory bytes, total request %d millicores %d memory bytes, score %d CPU %d memory",
pod.Name, node.Name,
allocatableResources.MilliCPU, allocatableResources.Memory,
totalResources.MilliCPU, totalResources.Memory,
cpuScore, memoryScore,
)
}
return schedulerapi.HostPriority{
Host: node.Name,
Score: int((cpuScore + memoryScore) / 2),
}
}
// LeastRequestedPriority is a priority function that favors nodes with fewer requested resources.
// It calculates the percentage of memory and CPU requested by pods scheduled on the node, and prioritizes
// based on the minimum of the average of the fraction of requested to capacity.
@ -90,7 +140,20 @@ func LeastRequestedPriority(pod *api.Pod, nodeNameToInfo map[string]*schedulerca
podResources := getNonZeroRequests(pod)
list := make(schedulerapi.HostPriorityList, 0, len(nodes))
for _, node := range nodes {
list = append(list, calculateResourceOccupancy(pod, podResources, node, nodeNameToInfo[node.Name]))
list = append(list, calculateUnusedPriority(pod, podResources, node, nodeNameToInfo[node.Name]))
}
return list, nil
}
// MostRequestedPriority is a priority function that favors nodes with most requested resources.
// It calculates the percentage of memory and CPU requested by pods scheduled on the node, and prioritizes
// based on the maximum of the average of the fraction of requested to capacity.
// Details: (cpu(10 * sum(requested) / capacity) + memory(10 * sum(requested) / capacity)) / 2
func MostRequestedPriority(pod *api.Pod, nodeNameToInfo map[string]*schedulercache.NodeInfo, nodes []*api.Node) (schedulerapi.HostPriorityList, error) {
podResources := getNonZeroRequests(pod)
list := make(schedulerapi.HostPriorityList, 0, len(nodes))
for _, node := range nodes {
list = append(list, calculateUsedPriority(pod, podResources, node, nodeNameToInfo[node.Name]))
}
return list, nil
}

155
plugin/pkg/scheduler/algorithm/priorities/priorities_test.go
View File

@ -411,6 +411,161 @@ func TestLeastRequested(t *testing.T) {
}
}
func TestMostRequested(t *testing.T) {
labels1 := map[string]string{
"foo": "bar",
"baz": "blah",
}
labels2 := map[string]string{
"bar": "foo",
"baz": "blah",
}
noResources := api.PodSpec{
Containers: []api.Container{},
}
cpuOnly := api.PodSpec{
NodeName: "machine1",
Containers: []api.Container{
{
Resources: api.ResourceRequirements{
Requests: api.ResourceList{
"cpu": resource.MustParse("1000m"),
"memory": resource.MustParse("0"),
},
},
},
{
Resources: api.ResourceRequirements{
Requests: api.ResourceList{
"cpu": resource.MustParse("2000m"),
"memory": resource.MustParse("0"),
},
},
},
},
}
cpuOnly2 := cpuOnly
cpuOnly2.NodeName = "machine2"
cpuAndMemory := api.PodSpec{
NodeName: "machine2",
Containers: []api.Container{
{
Resources: api.ResourceRequirements{
Requests: api.ResourceList{
"cpu": resource.MustParse("1000m"),
"memory": resource.MustParse("2000"),
},
},
},
{
Resources: api.ResourceRequirements{
Requests: api.ResourceList{
"cpu": resource.MustParse("2000m"),
"memory": resource.MustParse("3000"),
},
},
},
},
}
tests := []struct {
pod *api.Pod
pods []*api.Pod
nodes []*api.Node
expectedList schedulerapi.HostPriorityList
test string
}{
{
/*
Node1 scores (used resources) on 0-10 scale
CPU Score: (0 * 10 / 4000 = 0
Memory Score: (0 * 10) / 10000 = 0
Node1 Score: (0 + 0) / 2 = 0
Node2 scores (used resources) on 0-10 scale
CPU Score: (0 * 10 / 4000 = 0
Memory Score: (0 * 10 / 10000 = 0
Node2 Score: (0 + 0) / 2 = 0
*/
pod: &api.Pod{Spec: noResources},
nodes: []*api.Node{makeNode("machine1", 4000, 10000), makeNode("machine2", 4000, 10000)},
expectedList: []schedulerapi.HostPriority{{"machine1", 0}, {"machine2", 0}},
test: "nothing scheduled, nothing requested",
},
{
/*
Node1 scores on 0-10 scale
CPU Score: (3000 * 10 / 4000 = 7.5
Memory Score: (5000 * 10) / 10000 = 5
Node1 Score: (7.5 + 5) / 2 = 6
Node2 scores on 0-10 scale
CPU Score: (3000 * 10 / 6000 = 5
Memory Score: (5000 * 10 / 10000 = 5
Node2 Score: (5 + 5) / 2 = 5
*/
pod: &api.Pod{Spec: cpuAndMemory},
nodes: []*api.Node{makeNode("machine1", 4000, 10000), makeNode("machine2", 6000, 10000)},
expectedList: []schedulerapi.HostPriority{{"machine1", 6}, {"machine2", 5}},
test: "nothing scheduled, resources requested, differently sized machines",
},
{
/*
Node1 scores on 0-10 scale
CPU Score: (6000 * 10) / 10000 = 6
Memory Score: (0 * 10) / 20000 = 10
Node1 Score: (6 + 0) / 2 = 3
Node2 scores on 0-10 scale
CPU Score: (6000 * 10) / 10000 = 6
Memory Score: (5000 * 10) / 20000 = 2.5
Node2 Score: (6 + 2.5) / 2 = 4
*/
pod: &api.Pod{Spec: noResources},
nodes: []*api.Node{makeNode("machine1", 10000, 20000), makeNode("machine2", 10000, 20000)},
expectedList: []schedulerapi.HostPriority{{"machine1", 3}, {"machine2", 4}},
test: "no resources requested, pods scheduled with resources",
pods: []*api.Pod{
{Spec: cpuOnly, ObjectMeta: api.ObjectMeta{Labels: labels2}},
{Spec: cpuOnly, ObjectMeta: api.ObjectMeta{Labels: labels1}},
{Spec: cpuOnly2, ObjectMeta: api.ObjectMeta{Labels: labels1}},
{Spec: cpuAndMemory, ObjectMeta: api.ObjectMeta{Labels: labels1}},
},
},
{
/*
Node1 scores on 0-10 scale
CPU Score: (6000 * 10) / 10000 = 6
Memory Score: (5000 * 10) / 20000 = 2.5
Node1 Score: (6 + 2.5) / 2 = 4
Node2 scores on 0-10 scale
CPU Score: (6000 * 10) / 10000 = 6
Memory Score: (10000 * 10) / 20000 = 5
Node2 Score: (6 + 5) / 2 = 5
*/
pod: &api.Pod{Spec: cpuAndMemory},
nodes: []*api.Node{makeNode("machine1", 10000, 20000), makeNode("machine2", 10000, 20000)},
expectedList: []schedulerapi.HostPriority{{"machine1", 4}, {"machine2", 5}},
test: "resources requested, pods scheduled with resources",
pods: []*api.Pod{
{Spec: cpuOnly},
{Spec: cpuAndMemory},
},
},
}
for _, test := range tests {
nodeNameToInfo := schedulercache.CreateNodeNameToInfoMap(test.pods, test.nodes)
list, err := MostRequestedPriority(test.pod, nodeNameToInfo, test.nodes)
if err != nil {
t.Errorf("unexpected error: %v", err)
}
if !reflect.DeepEqual(test.expectedList, list) {
t.Errorf("%s: expected %#v, got %#v", test.test, test.expectedList, list)
}
}
}
func TestNewNodeLabelPriority(t *testing.T) {
label1 := map[string]string{"foo": "bar"}
label2 := map[string]string{"bar": "foo"}

2
plugin/pkg/scheduler/algorithmprovider/defaults/defaults.go
View File

@ -93,6 +93,8 @@ func init() {
factory.RegisterFitPredicate("HostName", predicates.PodFitsHost)
// Fit is determined by node selector query.
factory.RegisterFitPredicate("MatchNodeSelector", predicates.PodSelectorMatches)
// Optional, cluster-autoscaler friendly priority function - give used nodes higher priority.
factory.RegisterPriorityFunction("MostRequestedPriority", priorities.MostRequestedPriority, 1)
}
func defaultPredicates() sets.String {