volcano-scheduler-config

name	volcano-scheduler-config
description	View Volcano scheduler configuration. Check scheduler ConfigMap, actions, plugins, and tier settings.

Volcano Scheduler Configuration

View Volcano scheduler configuration to understand scheduling policies, enabled plugins, and actions. This skill helps diagnose configuration-related scheduling behaviors.

Scope: This skill is for diagnosis only. It retrieves configuration for analysis but does not modify any cluster state.

Usage

bash skills/core/volcano-scheduler-config/scripts/get-scheduler-config.sh [options]

Parameters

Parameter	Required	Description
--section SECTION	no	Show specific section: actions, plugins, tiers, all (default: all)
--format FORMAT	no	Output format: yaml, json, summary (default: summary)
--raw	no	Show raw ConfigMap data without parsing

Examples

Get summary of scheduler configuration:

bash skills/core/volcano-scheduler-config/scripts/get-scheduler-config.sh

View actions configuration only:

bash skills/core/volcano-scheduler-config/scripts/get-scheduler-config.sh --section actions

View plugins configuration:

bash skills/core/volcano-scheduler-config/scripts/get-scheduler-config.sh --section plugins

Show full YAML configuration:

bash skills/core/volcano-scheduler-config/scripts/get-scheduler-config.sh --format yaml

Get raw ConfigMap:

bash skills/core/volcano-scheduler-config/scripts/get-scheduler-config.sh --raw

Understanding Scheduler Configuration

Configuration Location

The Volcano scheduler configuration is stored in:

• Namespace: volcano-system
• ConfigMap: volcano-scheduler-configmap
• Key: volcano-scheduler.conf

Configuration Structure

actions: "enqueue, allocate, backfill"  # Pipeline order
tiers:
- plugins:
  - name: priority
  - name: gang
  - name: conformance
- plugins:
  - name: overcommit
  - name: drf
  - name: predicates
  - name: proportion
  - name: nodeorder
  - name: binpack

Actions

Actions define the two-phase scheduling pipeline:

1. Enqueue phase — PodGroup is admitted to the queue based on queue capacity (does the queue have enough deserved resources?)
2. Allocate phase — Individual pods are placed on nodes based on node resources, affinity, taints, etc.

A job can pass enqueue (PodGroup moves to Inqueue) but fail allocation (pods stay Pending) if node-level constraints block placement. This two-phase model explains the common scenario: "queue has capacity but pods won't schedule."

Actions in order:

Action	Required	Purpose
enqueue	Yes	Admit pod groups to queue
allocate	Yes	Allocate resources to pods
backfill	No	Fill idle resources with best-effort pods
preempt	No	Evict low-priority pods for high-priority
reclaim	No	Reclaim resources from over-allocated queues
elect	No	Select target workload (removed in v1.6+)

Tiers

Tiers divide plugins into priority levels:

• Tier 1: First to evaluate, results cannot be overridden
• Tier 2: Second to evaluate, lower priority

Common tier organization:

• Tier 1: Critical plugins (priority, gang, conformance)
• Tier 2: Resource and optimization plugins

Plugins

Critical Plugins

Plugin	Function	Critical For
gang	Gang scheduling	Batch jobs, ML training
priority	Priority sorting	Workload prioritization
conformance	Protect critical pods	System stability

Resource Plugins

Plugin	Function	Use Case
proportion	Fair share allocation	Multi-tenant clusters
drf	Dominant Resource Fairness	Fair GPU/CPU sharing
overcommit	Allow overcommit	Resource efficiency

Node Plugins

Plugin	Function	Use Case
predicates	Node filtering	Resource/affinity matching
nodeorder	Node ranking	Node selection optimization
binpack	Dense packing	Reduce fragmentation
numaaware	NUMA topology	HPC workloads

Queue Plugins

Plugin	Function	Use Case
priority	Queue ordering	Queue prioritization
proportion	Proportional share	Fair queue allocation

Diagnostic Use Cases

Case 1: Check If Gang Scheduling is Enabled

bash skills/core/volcano-scheduler-config/scripts/get-scheduler-config.sh --section plugins

Look for name: gang in the plugin list. If missing, Gang scheduling will not work.

Case 2: Verify Reclaim is Enabled

bash skills/core/volcano-scheduler-config/scripts/get-scheduler-config.sh --section actions

Look for reclaim in the actions list. If missing, queues cannot reclaim resources.

Case 3: Check Proportion Plugin Configuration

bash skills/core/volcano-scheduler-config/scripts/get-scheduler-config.sh --section plugins

Look for name: proportion. If missing, queue fair-share allocation is disabled.

Case 4: Compare with Default Configuration

Default configuration:

actions: "enqueue, allocate, backfill"
tiers:
- plugins:
  - name: priority
  - name: gang
    enablePreemptable: false
  - name: conformance
- plugins:
  - name: overcommit
  - name: drf
    enablePreemptable: false
  - name: predicates
  - name: proportion
  - name: nodeorder
  - name: binpack

If your configuration differs significantly, it may explain scheduling behaviors.

Case 5: Check Plugin Arguments

Some plugins accept arguments:

- name: overcommit
  arguments:
    overcommit-factor: "1.2"

Use --format yaml or --raw to see full plugin configurations including arguments.

Common Configuration Issues

Issue 1: Missing Gang Plugin

Symptom: PodGroups stay Pending, minMember never satisfied

Check:

bash skills/core/volcano-scheduler-config/scripts/get-scheduler-config.sh --section plugins | grep gang

Solution: Add gang plugin to configuration

Issue 2: Missing Reclaim Action

Symptom: Queues cannot reclaim resources from over-allocated queues

Check:

bash skills/core/volcano-scheduler-config/scripts/get-scheduler-config.sh --section actions | grep reclaim

Solution: Add reclaim to actions list

Issue 3: Wrong Action Order

Symptom: Unexpected scheduling behavior

Check:

bash skills/core/volcano-scheduler-config/scripts/get-scheduler-config.sh --section actions

Common orders:

• Default: enqueue, allocate, backfill
• With preemption: enqueue, allocate, backfill, preempt
• With reclaim: enqueue, allocate, backfill, reclaim
• Full: enqueue, allocate, backfill, preempt, reclaim

Important: enqueue must come before allocate. allocate must be present.

Issue 4: Plugin Tier Misconfiguration

Symptom: Priority/preemption not working as expected

Check:

bash skills/core/volcano-scheduler-config/scripts/get-scheduler-config.sh --section tiers

Guideline:

• Tier 1: Plugins that should not be overridden (priority, gang)
• Tier 2: Resource optimization plugins (proportion, binpack)

Configuration Options Reference

Plugin Arguments

Plugin	Argument	Default	Description
gang	enablePreemptable	true	Allow Gang pods to be preempted
overcommit	overcommit-factor	1.2	Multiplier for allocatable resources
drf	enablePreemptable	true	Allow DRF pods to be preempted
nodeorder	various weights	0	Node scoring weights
proportion	(none)	-	No arguments
predicates	GPUSharingEnable	false	Enable GPU sharing

Action-Specific Notes

Enqueue

• Evaluates jobEnqueueableFn from plugins
• Default overcommit-factor of 1.2 means 20% overcommit

Allocate

• Main allocation logic
• Calls allocate action for each tier

Backfill

• Only schedules best-effort pods (no resource requests)
• Ignores queue deserved resources

Preempt

• Requires priority plugin for comparison
• Requires preemptableFn from plugins

Reclaim

• Requires proportion plugin
• Requires reclaimableFn from plugins
• Reclaims from over-allocated queues

Environment Variables

Variable	Default	Description
VOLCANO_SCHEDULER_NS	volcano-system	Scheduler namespace
VOLCANO_SCHEDULER_CONFIG	volcano-scheduler-configmap	ConfigMap name

Output Formats

Summary Format (default)

Human-readable summary:

Scheduler Configuration
=======================
Actions: enqueue, allocate, backfill

Tier 1 Plugins:
  - priority
  - gang
  - conformance

Tier 2 Plugins:
  - overcommit
  - drf
  - predicates
  - proportion
  - nodeorder
  - binpack

YAML Format

Parsed YAML structure:

actions: "enqueue, allocate, backfill"
tiers:
  - plugins:
      - name: priority
      - name: gang

JSON Format

Machine-parseable:

{
  "actions": "enqueue, allocate, backfill",
  "tiers": [
    {
      "plugins": [
        {"name": "priority"},
        {"name": "gang"}
      ]
    }
  ]
}

Raw Format

ConfigMap raw output:

volcano-scheduler.conf:
---
actions: "enqueue, allocate, backfill"
tiers:
...

See Also

• volcano-queue-diagnose - Queue resource analysis
• volcano-gang-scheduling - Gang scheduling issues
• volcano-diagnose-pod - Pod scheduling diagnosis
• volcano-scheduler-logs - Scheduler decision logs