[slurm-users] MPI jobs via mirun vs. srun through PMIx.

Marcus Wagner wagner at itc.rwth-aachen.de
Tue Sep 17 08:12:40 UTC 2019

Hi Jürgen,

we set in our modules the variables $MPIEXEC and $FLAGS_MPI_BATCH and 
documented these.
This way, by changing the workloadmanagement system or the MPI or 
whatsoever does not change the documentation (at least on that point ;) )


On 9/17/19 9:02 AM, Juergen Salk wrote:
> * Loris Bennett <loris.bennett at fu-berlin.de> [190917 07:46]:
>>>> But I still don't get the point. Why should I favour `srun ./my_mpi_program´
>>>> over `mpirun ./my_mpi_program´? For me, both seem to do exactly the same
>>>> thing. No? Did I miss something?
>>>> Best regards
>>>> Jürgen
>>> Running a single job in isolation doesn't properly illustrate what slurm does in the larger sense.
>>> [...]
>> I think Jürgen may well be aware of what Slurm does in the larger sense.
> Dear Loris,
> thank you for your clarification. You are right. It seems that I have
> phrased my question somewhat misleadingly.
> For our next cluster we will switch from Moab/Torque to Slurm and have
> to adapt the documentation and example batch scripts for the users.
> Therefore, I wonder if and why we should recommend (or maybe even urge)
> our users to use srun instead of mpirun/mpiexec in their batch scripts
> for MPI jobs.
>> I suspect the question, which I also have, is more like:
>>    "What difference does it make whether I use 'srun' or 'mpirun' within
>>     a batch file started with 'sbatch'."
> That's exactly the question I wanted to ask.
> Thanks again.
> Best regards
> Jürgen

Marcus Wagner, Dipl.-Inf.

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