Tech Tip #30: Test small before you run big

Half a cluster's energy went on jobs that failed.

Video created by explainapaper.com

The problem

On a shared cluster, jobs fail part-way through on a bad input, a memory limit or an unhandled edge case, then get fixed and resubmitted. A study of a Dutch national cluster found about half its energy went on jobs that ended unsuccessfully.

The fix you can use today

  • Run on a small input first.
  • Set realistic memory and time limits, and validate inputs before the long run.
  • Checkpoint long jobs so a failure doesn't restart from zero.

Researchers in Amsterdam and Vienna found that half of one cluster's energy went on jobs that failed. GreenCode is exploring checks like this for jobs on shared clusters.

Tools that help

  • Slurm energy accounting: records the energy each job consumed, so users can look it up after the run
  • Green Algorithms calculator: estimates the carbon footprint of a computation from its runtime, hardware and location
  • CodeCarbon: a Python package that estimates the energy and CO2 of a run from hardware power and regional grid intensity

How GreenCode helps

GreenCode helps tackle this by establishing a repeatable energy baseline for research software and measuring again after each optimisation. A university research computing cluster is one of the project's use cases. More on this.

Tags

#hpc#research-software#testing

Sources

Transcript

Half of one cluster's energy went on jobs that failed. On a shared computer cluster, long jobs fail part-way through. A bad input, a memory limit, or a case nobody handled. Then they are fixed and sent again. Researchers in Amsterdam and Vienna studied one Dutch national cluster. About half its energy went on jobs that ended in failure. Here is the fix you can use today. Run on a small input first. Set realistic memory and time limits, and check inputs before the long run. Save checkpoints, so a failure does not restart from zero. A job sent three times has run four times. Estimate a run's carbon first, using tools like the Green Algorithms calculator and CodeCarbon. Afterwards, Slurm's energy accounting shows the energy each job used. GreenCode helps tackle this by measuring research code's energy before and after each fix. A university research cluster is one of its test beds. That was GreenCode Tech Tip number thirty. Follow for the next tip, and find more on greencode.ai/tech-tips.

All GreenCode Tech Tips · All GreenCode videos

  • Tip #30
  • For Ops and infrastructure
  • Length 1:09
  • Category HPC, embedded, mobile and games
GreenCode

Want this checked on your own system? Talk to the GreenCode team.

Get in touch