qos.go

Documentation: k8s.io/kubernetes/pkg/apis/core/v1/helper/qos

     1  /*
     2  Copyright 2015 The Kubernetes Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package qos
    18  
    19  import (
    20  	v1 "k8s.io/api/core/v1"
    21  	"k8s.io/apimachinery/pkg/api/resource"
    22  	"k8s.io/apimachinery/pkg/util/sets"
    23  	"k8s.io/kubernetes/pkg/apis/core"
    24  )
    25  
    26  var supportedQoSComputeResources = sets.NewString(string(core.ResourceCPU), string(core.ResourceMemory))
    27  
    28  // QOSList is a set of (resource name, QoS class) pairs.
    29  type QOSList map[v1.ResourceName]v1.PodQOSClass
    30  
    31  func isSupportedQoSComputeResource(name v1.ResourceName) bool {
    32  	return supportedQoSComputeResources.Has(string(name))
    33  }
    34  
    35  // GetPodQOS returns the QoS class of a pod persisted in the PodStatus.QOSClass field.
    36  // If PodStatus.QOSClass is empty, it returns value of ComputePodQOS() which evaluates pod's QoS class.
    37  func GetPodQOS(pod *v1.Pod) v1.PodQOSClass {
    38  	if pod.Status.QOSClass != "" {
    39  		return pod.Status.QOSClass
    40  	}
    41  	return ComputePodQOS(pod)
    42  }
    43  
    44  // ComputePodQOS evaluates the list of containers to determine a pod's QoS class. This function is more
    45  // expensive than GetPodQOS which should be used for pods having a non-empty .Status.QOSClass.
    46  // A pod is besteffort if none of its containers have specified any requests or limits.
    47  // A pod is guaranteed only when requests and limits are specified for all the containers and they are equal.
    48  // A pod is burstable if limits and requests do not match across all containers.
    49  func ComputePodQOS(pod *v1.Pod) v1.PodQOSClass {
    50  	requests := v1.ResourceList{}
    51  	limits := v1.ResourceList{}
    52  	zeroQuantity := resource.MustParse("0")
    53  	isGuaranteed := true
    54  	allContainers := []v1.Container{}
    55  	allContainers = append(allContainers, pod.Spec.Containers...)
    56  	allContainers = append(allContainers, pod.Spec.InitContainers...)
    57  	for _, container := range allContainers {
    58  		// process requests
    59  		for name, quantity := range container.Resources.Requests {
    60  			if !isSupportedQoSComputeResource(name) {
    61  				continue
    62  			}
    63  			if quantity.Cmp(zeroQuantity) == 1 {
    64  				delta := quantity.DeepCopy()
    65  				if _, exists := requests[name]; !exists {
    66  					requests[name] = delta
    67  				} else {
    68  					delta.Add(requests[name])
    69  					requests[name] = delta
    70  				}
    71  			}
    72  		}
    73  		// process limits
    74  		qosLimitsFound := sets.NewString()
    75  		for name, quantity := range container.Resources.Limits {
    76  			if !isSupportedQoSComputeResource(name) {
    77  				continue
    78  			}
    79  			if quantity.Cmp(zeroQuantity) == 1 {
    80  				qosLimitsFound.Insert(string(name))
    81  				delta := quantity.DeepCopy()
    82  				if _, exists := limits[name]; !exists {
    83  					limits[name] = delta
    84  				} else {
    85  					delta.Add(limits[name])
    86  					limits[name] = delta
    87  				}
    88  			}
    89  		}
    90  
    91  		if !qosLimitsFound.HasAll(string(v1.ResourceMemory), string(v1.ResourceCPU)) {
    92  			isGuaranteed = false
    93  		}
    94  	}
    95  	if len(requests) == 0 && len(limits) == 0 {
    96  		return v1.PodQOSBestEffort
    97  	}
    98  	// Check is requests match limits for all resources.
    99  	if isGuaranteed {
   100  		for name, req := range requests {
   101  			if lim, exists := limits[name]; !exists || lim.Cmp(req) != 0 {
   102  				isGuaranteed = false
   103  				break
   104  			}
   105  		}
   106  	}
   107  	if isGuaranteed &&
   108  		len(requests) == len(limits) {
   109  		return v1.PodQOSGuaranteed
   110  	}
   111  	return v1.PodQOSBurstable
   112  }
   113
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