Workload Priority Class

A WorkloadPriorityClass allows you to control the Workload’s priority without affecting the pod’s priority. This feature is useful for these cases:

• want to prioritize workloads that remain inactive for a specific duration
• want to set a lower priority for development workloads and higher priority for production workloads

A sample WorkloadPriorityClass looks like the following:

apiVersion: kueue.x-k8s.io/v1beta2
kind: WorkloadPriorityClass
metadata:
  name: sample-priority
value: 10000
description: "Sample priority"

WorkloadPriorityClass objects are cluster scoped, so they can be used by a job in any namespace.

How to use WorkloadPriorityClass on Jobs

You can specify the WorkloadPriorityClass by setting the label kueue.x-k8s.io/priority-class.

apiVersion: batch/v1
kind: Job
metadata:
  name: sample-job
  labels:
    kueue.x-k8s.io/queue-name: user-queue
    kueue.x-k8s.io/priority-class: sample-priority
spec:
...

Kueue generates the following Workload for the Job above. The PriorityClassName field can accept either PriorityClass or WorkloadPriorityClass name as a value. To distinguish, when using WorkloadPriorityClass, a priorityClassSource field has the kueue.x-k8s.io/workloadpriorityclass value. When using PriorityClass, a priorityClassSource field has the scheduling.k8s.io/priorityclass value.

apiVersion: kueue.x-k8s.io/v1beta2
kind: Workload
metadata:
  name: job-sample-job-7f173
spec:
  priorityClassSource: kueue.x-k8s.io/workloadpriorityclass
  priorityClassName: sample-priority
  priority: 10000
  queueName: user-queue
...

For other job frameworks, you can set WorkloadPriorityClass using the same label. The Following is an example of MPIJob.

apiVersion: kubeflow.org/v2beta1
kind: MPIJob
metadata:
  name: pi
  labels:
    kueue.x-k8s.io/queue-name: user-queue
    kueue.x-k8s.io/priority-class: sample-priority
spec:
...

The relationship between pod’s priority and workload’s priority

When creating a Workload for a given job, Kueue considers the following scenarios:

1. A job specifies both WorkloadPriorityClass and PriorityClass

• WorkloadPriorityClass is used for the workload’s priority.
• PriorityClass is used for the pod’s priority.

2. A job specifies only WorkloadPriorityClass

• WorkloadPriorityClass is used for the workload’s priority.
• WorkloadPriorityClass is not used for pod’s priority.

3. A job specifies only PriorityClass

• PriorityClass is used for the workload’s priority and pod’s priority.

In certain job frameworks, there are CRDs that:

• Define multiple pod specs, where each can have their own pod priority, or
• Define the overall pod priority in a dedicated field. By default kueue will take the PriorityClassName of the first PodSet having one set, however the integration of the CRD with Kueue can implement JobWithPriorityClass interface to change this behavior. You can read the code for each job integration to learn how the priority class is obtained.

Where workload’s priority is used

The priority of workloads is used for:

• Sorting the workloads in the ClusterQueues.
• Determining whether a workload can preempt others.

Workload’s priority values are always mutable

The Workload’s Priority field is always mutable. If a Workload has been pending for a while, you can consider updating its priority to execute it earlier, based on your own policies. Workload’s PriorityClassSource and PriorityClassName fields are immutable.

What’s next?

• Learn how to run jobs
• Learn how to run jobs with workload priority
• Read the API reference for WorkloadPriorityClass