Nodeorder

Overview

The Nodeorder plugin is a scheduling optimization strategy that scores nodes from various dimensions through simulated assignments to find the node that is best suited for the current task. The scoring parameters are configured by the user.

How It Works

The Nodeorder plugin implements the NodeOrderFn to score all nodes for a task using a series of scoring algorithms. The node with the highest score is considered to be the most suitable node for the task.

Scoring dimensions include:

• Affinity: Node and pod affinity/anti-affinity scores
• LeastRequestedResource: Prefers nodes with more available resources
• MostRequestedResource: Prefers nodes with fewer available resources (consolidation)
• BalancedResourceAllocation: Prefers nodes with balanced resource usage
• ImageLocality: Prefers nodes that already have the container images

Scenario

The Nodeorder plugin provides scoring criteria across multiple dimensions for scheduling. The combination of different dimensions enables users to flexibly configure appropriate scheduling policies according to their own needs.

Workload Distribution

By adjusting weights for different scoring dimensions, you can control how workloads are distributed across the cluster:

• Use LeastRequestedResource to spread workloads evenly
• Use MostRequestedResource to consolidate workloads (similar to Binpack)

Image Locality Optimization

For large container images, using ImageLocality scoring can reduce pod startup time by preferring nodes that already have the required images.

Affinity Optimization

The Affinity dimension ensures that pods are placed according to their affinity and anti-affinity rules.

Configuration

The Nodeorder plugin is enabled in the scheduler ConfigMap with configurable weights:

tiers:
- plugins:
  - name: predicates
  - name: nodeorder
    arguments:
      nodeorder.weight: 10
      nodeorder.leastrequested.enable: true
      nodeorder.mostrequested.enable: false
      nodeorder.nodeaffinity.enable: true
      nodeorder.podaffinity.enable: true
      nodeorder.balancedresource.enable: true
      nodeorder.imagelocality.enable: true

Configuration Parameters

Parameter	Description	Default
nodeorder.weight	Overall weight of the Nodeorder plugin	1
nodeorder.leastrequested.enable	Enable least requested resource scoring	true
nodeorder.mostrequested.enable	Enable most requested resource scoring	false
nodeorder.nodeaffinity.enable	Enable node affinity scoring	true
nodeorder.podaffinity.enable	Enable pod affinity scoring	true
nodeorder.balancedresource.enable	Enable balanced resource scoring	true
nodeorder.imagelocality.enable	Enable image locality scoring	true
nodeorder.leastrequested.weight	Weight for least requested scoring	1
nodeorder.mostrequested.weight	Weight for most requested scoring	1
nodeorder.nodeaffinity.weight	Weight for node affinity scoring	1
nodeorder.podaffinity.weight	Weight for pod affinity scoring	1
nodeorder.balancedresource.weight	Weight for balanced resource scoring	1
nodeorder.imagelocality.weight	Weight for image locality scoring	1

Example

Configuration for Spreading Workloads

apiVersion: v1
kind: ConfigMap
metadata:
  name: volcano-scheduler-configmap
  namespace: volcano-system
data:
  volcano-scheduler.conf: |
    actions: "enqueue, allocate, backfill"
    tiers:
    - plugins:
      - name: priority
      - name: gang
    - plugins:
      - name: predicates
      - name: nodeorder
        arguments:
          nodeorder.leastrequested.enable: true
          nodeorder.leastrequested.weight: 2
          nodeorder.balancedresource.enable: true

Configuration for Consolidating Workloads

apiVersion: v1
kind: ConfigMap
metadata:
  name: volcano-scheduler-configmap
  namespace: volcano-system
data:
  volcano-scheduler.conf: |
    actions: "enqueue, allocate, backfill"
    tiers:
    - plugins:
      - name: priority
      - name: gang
    - plugins:
      - name: predicates
      - name: nodeorder
        arguments:
          nodeorder.mostrequested.enable: true
          nodeorder.mostrequested.weight: 2
          nodeorder.leastrequested.enable: false

Job with Pod Affinity

apiVersion: batch.volcano.sh/v1alpha1
kind: Job
metadata:
  name: affinity-job
spec:
  schedulerName: volcano
  minAvailable: 2
  tasks:
  - replicas: 2
    name: worker
    template:
      spec:
        affinity:
          podAffinity:
            preferredDuringSchedulingIgnoredDuringExecution:
            - weight: 100
              podAffinityTerm:
                labelSelector:
                  matchLabels:
                    app: cache
                topologyKey: kubernetes.io/hostname
        containers:
        - name: worker
          image: busybox

The Nodeorder plugin will score nodes higher if they already have pods matching the affinity rules.