112 lines
4.0 KiB
Go
112 lines
4.0 KiB
Go
/*
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Copyright 2019 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 scheduling
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import (
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"reflect"
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"k8s.io/autoscaler/cluster-autoscaler/utils"
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apiv1 "k8s.io/api/core/v1"
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"k8s.io/autoscaler/cluster-autoscaler/utils/drain"
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pod_utils "k8s.io/autoscaler/cluster-autoscaler/utils/pod"
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)
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// SimilarPodsSchedulingInfo data structure is used to avoid running predicates #pending_pods * #nodes
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// times (which turned out to be very expensive if there are thousands of pending pods).
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// This optimization is based on the assumption that if there are that many pods they're
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// likely created by controllers (deployment, replication controller, ...).
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// So instead of running all predicates for every pod we first check whether we've
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// already seen identical pod (in this step we're not binpacking, just checking if
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// the pod would fit anywhere right now) and if so we use the result we already
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// calculated.
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// To decide if two pods are similar enough we check if they have identical label
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// and spec and are owned by the same controller. The problem is the whole
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// SimilarPodsSchedulingInfo struct is not hashable and keeping a list and running deep
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// equality checks would likely also be expensive. So instead we use controller
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// UID as a key in initial lookup and only run full comparison on a set of
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// SimilarPodsSchedulingInfo created for pods owned by this controller.
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type SimilarPodsSchedulingInfo struct {
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spec apiv1.PodSpec
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labels map[string]string
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}
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// Match tests if given pod matches SimilarPodsSchedulingInfo
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func (psi *SimilarPodsSchedulingInfo) Match(pod *apiv1.Pod) bool {
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return reflect.DeepEqual(pod.Labels, psi.labels) && utils.PodSpecSemanticallyEqual(pod.Spec, psi.spec)
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}
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const maxPodsPerOwnerRef = 10
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// SimilarPodsScheduling stores mapping from controller ref to SimilarPodsSchedulingInfo
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type SimilarPodsScheduling struct {
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items map[string][]SimilarPodsSchedulingInfo
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overflowingControllers map[string]bool
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}
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// NewSimilarPodsScheduling creates a new SimilarPodsScheduling
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func NewSimilarPodsScheduling() *SimilarPodsScheduling {
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return &SimilarPodsScheduling{
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items: make(map[string][]SimilarPodsSchedulingInfo),
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overflowingControllers: make(map[string]bool),
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}
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}
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// IsSimilarUnschedulable returns scheduling info for given pod if matching one exists in SimilarPodsScheduling
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func (p *SimilarPodsScheduling) IsSimilarUnschedulable(pod *apiv1.Pod) bool {
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ref := drain.ControllerRef(pod)
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if ref == nil {
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return false
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}
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uid := string(ref.UID)
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if infos, found := p.items[uid]; found {
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for _, info := range infos {
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if info.Match(pod) {
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return true
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}
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}
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}
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return false
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}
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// SetUnschedulable sets scheduling info for given pod in SimilarPodsScheduling
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func (p *SimilarPodsScheduling) SetUnschedulable(pod *apiv1.Pod) {
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ref := drain.ControllerRef(pod)
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if ref == nil || pod_utils.IsDaemonSetPod(pod) {
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return
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}
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uid := string(ref.UID)
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pm := p.items[uid]
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if len(pm) >= maxPodsPerOwnerRef {
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// Too many different pods per owner reference. Don't cache the
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// entry to avoid O(N) search in Get(). It would defeat the
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// benefits from caching anyway.
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p.overflowingControllers[uid] = true
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return
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}
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p.items[uid] = append(pm, SimilarPodsSchedulingInfo{
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spec: pod.Spec,
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labels: pod.Labels,
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})
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}
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// OverflowingControllerCount returns the number of controllers that had too
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// many different pods to be effectively cached.
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func (p *SimilarPodsScheduling) OverflowingControllerCount() int {
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return len(p.overflowingControllers)
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}
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