M3 User Guide

QoS (Quality of Service)

We have implemented Quality of Service (QoS) starting 6th of June 2018.

The QoS can be added to each job that is submitted to Slurm. The quality of service associated with a job will affect the job in three ways:

  1. Job Scheduling Priority
  2. Job Preemption
  3. Job Limits

How to run jobs with QoS

A table to show the differences between QoS:

Queue Description Max Walltime Max GPU per user Max CPU per user Priority Preemption
normal Default QoS for every job 7 days 4 200 50 No
rtq QoS for interactive job 48 hours 4 36 200 No
irq QoS for interruptable job 7 days No limit No limit 200 Yes
shortq QoS for job with short walltime 30 mins 10 280 250 No

Explanation

These QoS are applied to the partition comp.

--qos=normal

This is the QoS for all the jobs that do not specify a QoS. Jobs that run here won’t be interrupted.

--qos=rtq

This is intended to be used by jobs that have an instrument or a real-time scenario and therefore can’t be interrupted and must be available on demand. You can only use a few CPUs and GPUs, but jobs will start as soon as possible (before normal jobs).

qos=irq This is intended to be used by jobs that are interruptible. To use the irq you have to be prepared to either restart from scratch (if the job was short anyway) or restart from a checkpoint. Jobs will start very quickly and use all the availble resources but may be stopped at short notice to allow shortq or rtq jobs to run.

The mechanism to checkpoint depends on the software that you are running.

Please contact us if you have any questions with regards to job checkpointing.

--qos=shortq This is intended to be used by short and uninterruptible jobs. These jobs will run before normal but the walltime is limited.

An example of Slurm GPU job script

#!/bin/bash
#SBATCH --job-name=MyJob
#SBATCH --account=<my_account>
#SBATCH --qos=<irq,shortq,rtq>
#SBATCH --gres=gpu:<K80,P100,V100>:1
#SBATCH --ntasks=2

<GPU processing program>

An example Slurm job script

#!/bin/bash
#SBATCH --job-name=MyJob
#SBATCH --account=<my_account>
#SBATCH --qos=<irq,shortq,rtq>
#SBATCH --ntasks=2

openmpi/1.10.7-mlx
mpirun <program>