pkg/noderesources/resource_allocation.go

/*
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.
*/

// This file was copied from the main k/k repo and defaultResourcesToWeightMap was added.
// See: https://github.com/kubernetes/kubernetes/blob/release-1.19/pkg/scheduler/framework/plugins/noderesources/resource_allocation.go

package noderesources

import (
	v1 "k8s.io/api/core/v1"
	"k8s.io/klog/v2"
	"k8s.io/kubernetes/pkg/scheduler/framework"
	schedutil "k8s.io/kubernetes/pkg/scheduler/util"
)

// resourceToWeightMap contains resource name and weight.
type resourceToWeightMap map[v1.ResourceName]int64

// defaultResourcesToWeightMap is used to set default resourceToWeight map for CPU and memory.
// The base unit for CPU is millicore, while the base using for memory is a byte.
// The default CPU weight is 1<<20 and default memory weight is 1. That means a millicore
// has a weighted score equivalent to 1 MiB.
var defaultResourcesToWeightMap = resourceToWeightMap{v1.ResourceMemory: 1, v1.ResourceCPU: 1 << 20}

// resourceAllocationScorer contains information to calculate resource allocation score.
type resourceAllocationScorer struct {
	Name                string
	scorer              func(requested, allocatable resourceToValueMap) int64
	resourceToWeightMap resourceToWeightMap
}

// resourceToValueMap contains resource name and score.
type resourceToValueMap map[v1.ResourceName]int64

// score will use `scorer` function to calculate the score.
func (r *resourceAllocationScorer) score(
	pod *v1.Pod,
	nodeInfo *framework.NodeInfo) (int64, *framework.Status) {
	node := nodeInfo.Node()
	if node == nil {
		return 0, framework.NewStatus(framework.Error, "node not found")
	}
	if r.resourceToWeightMap == nil {
		return 0, framework.NewStatus(framework.Error, "resources not found")
	}
	requested := make(resourceToValueMap, len(r.resourceToWeightMap))
	allocatable := make(resourceToValueMap, len(r.resourceToWeightMap))
	for resource := range r.resourceToWeightMap {
		allocatable[resource], requested[resource] = calculateResourceAllocatableRequest(nodeInfo, pod, resource)
	}

	score := r.scorer(requested, allocatable)

	if klog.V(10).Enabled() {
		klog.InfoS("Resources and score",
			"podName", pod.Name, "nodeName", node.Name, "scorer", r.Name,
			"allocatableResources", allocatable, "requestedResources", requested,
			"score", score)
	}

	return score, nil
}

// calculateResourceAllocatableRequest returns resources Allocatable and Requested values
func calculateResourceAllocatableRequest(nodeInfo *framework.NodeInfo, pod *v1.Pod, resource v1.ResourceName) (int64, int64) {
	podRequest := calculatePodResourceRequest(pod, resource)
	switch resource {
	case v1.ResourceCPU:
		return nodeInfo.Allocatable.MilliCPU, (nodeInfo.NonZeroRequested.MilliCPU + podRequest)
	case v1.ResourceMemory:
		return nodeInfo.Allocatable.Memory, (nodeInfo.NonZeroRequested.Memory + podRequest)

	case v1.ResourceEphemeralStorage:
		return nodeInfo.Allocatable.EphemeralStorage, (nodeInfo.Requested.EphemeralStorage + podRequest)
	default:
		if schedutil.IsScalarResourceName(resource) {
			return nodeInfo.Allocatable.ScalarResources[resource], (nodeInfo.Requested.ScalarResources[resource] + podRequest)
		}
	}
	if klog.V(10).Enabled() {
		klog.InfoS("Requested resource not considered for node score calculation",
			"resource", resource,
		)
	}
	return 0, 0
}

// calculatePodResourceRequest returns the total non-zero requests. If Overhead is defined for the pod and the
// PodOverhead feature is enabled, the Overhead is added to the result.
// podResourceRequest = max(sum(podSpec.Containers), podSpec.InitContainers) + overHead
func calculatePodResourceRequest(pod *v1.Pod, resource v1.ResourceName) int64 {
	var podRequest int64
	for i := range pod.Spec.Containers {
		container := &pod.Spec.Containers[i]
		qty := schedutil.GetRequestForResource(resource, &container.Resources.Requests, true)
		podRequest += qty.Value()
	}

	for i := range pod.Spec.InitContainers {
		initContainer := &pod.Spec.InitContainers[i]
		qty := schedutil.GetRequestForResource(resource, &initContainer.Resources.Requests, true)
		if value := qty.Value(); podRequest < value {
			podRequest = value
		}
	}

	// If Overhead is being utilized, add to the total requests for the pod
	if pod.Spec.Overhead != nil {
		if quantity, found := pod.Spec.Overhead[resource]; found {
			podRequest += quantity.Value()
		}
	}

	return podRequest
}