GPU Etiquette and Best Practices

Last updated on 2026-08-27 | Edit this page

Overview

Questions

  • Why is GPU etiquette important?
  • How long can you run GPU jobs?
  • What are fair usage practices?
  • How do you share GPU resources?

Objectives

  • Understand GPU resource sharing
  • Practice fair usage of limited resources
  • Know time and resource limits
  • Implement GPU best practices

GPU Resource Limits

Per-User Limits

  • Max concurrent GPUs: Per-account limits apply
  • Max per job: Check current policy
  • Max time: 720 hours (30 days)
  • Queue priority: Fair-share based on usage

Cluster Limits

  • Total GPUs: Limited shared resource
  • Peak utilization: Usually >80%
  • High demand: Especially A100 and L40S

Fair Usage Practices

1. Request Appropriate Resources

BASH 

# Not: 4x A100 80GB for testing
# Use L40S for testing

#SBATCH --gres=gpu:l40s:1  # For quick test
#SBATCH --time=00:30:00

2. Don’t Hog Resources

BASH 

# Bad: Run job for 30 days when only 4 hours needed
#SBATCH --time=720:00:00

# Good: Request actual time needed
#SBATCH --time=04:00:00

3. Avoid Interactive Idle Sessions

BASH 

# Don't do this:
srun -p gpu --gres=gpu:a100:1 --time=24:00:00 --pty bash
# ... leave running overnight

# Instead: Close when not using
exit  # Release GPU immediately
Callout

GPU Idle Time Costs Everyone

A single A100 left idle: - Costs ~$2-3 per hour in compute time - Blocks other researchers from using it - Wastes shared research budget

If you need a long session, use Jupyter (closes idle sessions) or batch jobs.

4. Batch Similar Jobs

Instead of:

BASH 

# 100 separate 1-minute GPU jobs
for i in {1..100}; do
    sbatch job_$i.sh
done

Batch them:

BASH 

# One job with 100 iterations
sbatch batch_job.sh

Monitoring Your Usage

Check how many GPUs you’re using:

BASH 

squeue -u $USER | grep gpu
# Count running jobs with --gres=gpu

Check past usage:

BASH 

sacct -u $USER --format=JobName,Partition,NodeList,GRES,State,Elapsed

Sharing GPU Nodes

Multiple users may run on same node. Be considerate: - Don’t monopolize node resources - Monitor your memory usage - Release GPUs immediately when done - Don’t interfere with others’ jobs

Best Practices Summary

  1. Test with small jobs first
    • Use L40S, small batch size
    • Run for 15-30 minutes
    • Verify code works
  2. Scale up incrementally
    • If test works, try larger GPU
    • Increase batch size gradually
    • Monitor memory usage
  3. Clean up after yourself
    • Delete temporary files
    • Exit interactive sessions
    • Cancel long jobs if not needed
  4. Share responsibility
    • Leave GPUs for others
    • Don’t submit unnecessary jobs
    • Report wasteful jobs you see
  5. Plan ahead
    • Submit jobs during off-peak (evening, weekends)
    • Peak: business hours, Monday-Friday
    • Expect longer waits during peaks

Example: Responsible Workflow

BASH 

# Step 1: Test on CPU
python3 train.py --gpu false --epochs 1

# Step 2: Quick GPU test
sbatch --gres=gpu:l40s:1 --time=00:30:00 train.sh

# Step 3: If works, scale up
sbatch --gres=gpu:a100:1 --time=04:00:00 train.sh

# Step 4: Monitor and iterate
squeue -u $USER
Challenge

Challenge: Resource Audit

A system administrator shows you the following squeue output for a single user:

JOBID  PARTITION  NAME          USER    ST  TIME       NODES  GRES          TIME_LIMIT
44201  gpu        interactive   jsmith  R   18:32:05   1      gpu:a100:2    24:00:00
44215  gpu        train_v1      jsmith  R   06:15:22   1      gpu:a100:1    72:00:00
44216  gpu        test_small    jsmith  R   00:02:14   1      gpu:l40s:1    48:00:00
44220  gpu        debug_run     jsmith  R   00:45:30   1      gpu:l40s:1    24:00:00

The administrator also notes that nvidia-smi on the interactive job (44201) shows 0% GPU utilization, and the test_small job (44216) finishes its work in under 5 minutes.

  1. Identify three wasteful patterns in this user’s GPU usage.
  2. Suggest a specific improvement for each.

Wasteful pattern 1: Idle interactive session hogging 2 A100s

Job 44201 is an interactive session that has been running for over 18 hours with 0% GPU utilization, holding 2 A100 GPUs (the most in-demand resource on the cluster).

Improvement: Close interactive sessions when not actively using them. If the user needs occasional interactive access, request a single L40S for shorter periods:

BASH 

srun -p gpu --gres=gpu:l40s:1 --time=02:00:00 --pty bash

Wasteful pattern 2: Massively over-allocated time limits

Job 44216 (test_small) has a 48-hour time limit but finishes in under 5 minutes. Job 44215 has a 72-hour limit. Over-requesting time blocks the scheduler from backfilling other users’ jobs into that slot.

Improvement: Set time limits close to actual need. For a 5-minute test job:

BASH 

#SBATCH --time=00:30:00   # 30 minutes is plenty for a quick test

Wasteful pattern 3: Using premium GPUs for small/debug workloads

Job 44216 uses an L40S (48GB) for a small test, and job 44220 could potentially be consolidated. Small tests and debugging do not need high-end GPUs.

Improvement: Use L40S for testing and debugging, reserve A100 and RTX PRO 6000 for production training runs that actually need the memory and compute:

BASH 

# For testing
#SBATCH --gres=gpu:l40s:1
#SBATCH --time=00:30:00

# Only scale up when the code is verified
#SBATCH --gres=gpu:a100:1
#SBATCH --time=04:00:00

Overall, this user is consuming 4 GPUs (including 3 A100s) simultaneously, most of which are idle or over-provisioned. Right-sizing would free resources for other researchers.

Key Points
  • Sagehen HPC has limited GPUs; fair sharing is essential
  • Request appropriate GPU type for your workload
  • Don’t monopolize GPUs or leave idle
  • Test on L40S before scaling to A100
  • Clean up after jobs complete
  • Monitor your usage with squeue
  • Respect other users’ resource needs