Workload Aware Scheduling on Jobset

Gang Scheduling

Sun, 31 May 2026 00:00:00 +0000

This example configures gang scheduling so that all 6 pods (3 replicas × 2 completions) in a JobSet must be schedulable before any of them are admitted.

Step 1: Create the Workload

The Workload references the JobSet and defines a pod group template with a gang scheduling policy:

apiVersion: scheduling.k8s.io/v1alpha2
kind: Workload
metadata:
 name: js-abc
spec:
 controllerRef:
 apiGroup: jobset.x-k8s.io
 kind: JobSet
 name: js
 podGroupTemplates:
 - name: workers
 schedulingPolicy:
 gang:
 minCount: 6

The controllerRef links the Workload to the JobSet. The podGroupTemplates entry defines a gang scheduling policy requiring a minimum of 6 pods to be schedulable.

Preemption

Sun, 31 May 2026 00:00:00 +0000

When the WorkloadAwarePreemption feature gate is enabled, the scheduler can preempt entire pod groups to make room for higher-priority gang-scheduled workloads.

The Problem

Without workload-aware preemption, the scheduler preempts individual pods. This can cause problems for gang-scheduled workloads — preempting some pods from a running gang breaks the entire workload, and freeing only a subset of the required resources may not be enough to admit the pending gang.

How It Works

With workload-aware preemption, the scheduler understands that pods belong to a group and makes preemption decisions at the group level. This means:

Topology Aware Scheduling

Sun, 31 May 2026 00:00:00 +0000

Topology Aware Scheduling (TAS) ensures that all pods in a gang are placed within the same network topology domain (e.g., the same rack, block, or data center zone). This is critical for distributed training workloads where inter-pod communication latency directly impacts performance.

Prerequisites

In addition to the general WAS prerequisites, you must:

Enable the TopologyAwareWorkloadScheduling feature gate. This feature gate is included in the kind cluster configuration and is required for topology-aware placement.