Translations of this page:

Interactive use

Interactive runs might be needed in some special cases. Use them only when you are present and release resources immediately when ready. Do not use them for normal calculations but use automated calculations instead.

Interactive calculations tend to lead to:

  • Inefficient use of system resources
  • Inefficient use of software licenses

Other issues:

  • Security updates might need rebooting of login node which means that interactive runs are lost

Connection

Linux

Create connection with X forwarding enabled.

ssh -X somehost.lut.fi

Windows

You need to have X server installed in your local Windows computer. Use Xming.

Make sure that X forwarding is enabled in settings of PuTTY. Check from Connection > SSH > X11: Set up X11 forwarding

Reserve resources

First it's good to check if there are free nodes for interactive use with sinfo. Then use srun and normal SLURM options to reserve resources.

Command to reserve resources depends on which kind of job is going to be started (adapt following examples to your needs):

  1. If you use MPI parallelization (typical HPC calculation code):
    srun -p <slurm partition> -n <number of cores> -t <maxtime> --x11=first --pty $SHELL
  2. If you use only threaded software (for example compilation):
    srun -p <slurm partition> -N 1 -n 1 -c <number of cores> -t <maxtime> --x11=first --pty $SHELL
  3. If you use MPI+OpenMP hybrid parallelization:
    srun -p <slurm partition> -N <number of nodes> --ntasks-per-node=<number of processes per node> -c <number of cores per process> -t <maxtime> --x11=first --pty $SHELL

Example (node from partition draco with all 4 cores for 6 hours to be used with MPI parallelization):

srun -p draco -n 4 -t 06:00:00 --x11=first --pty $SHELL

Next SLURM gives message

srun: job <jobid> queued and waiting for resources

When there is free resources in cluster following is shown and command line is dropped:

srun: job <jobid> has been allocated resources

Now you can start the actual interactive use. See separate instructions from software pages. Next you should check carefully that software is actually able to use all resources reserved. Threaded software might actually use only single CPU core if resources are not reserved correctly. Just use another terminal window to connect to node which you are using and check with top or htop command.

 
/opt/webdata/webroot/wiki/data/pages/en/hpc/usage/interactive.txt · Last modified: 2018/12/12 09:21 by vrintala
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