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Subject: Re: [OMPI devel] RFC: Force Slurm to use PMI-1 unless PMI-2 is specifically requested
From: Christopher Samuel (samuel_at_[hidden])
Date: 2014-05-06 23:49:25


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On 07/05/14 13:37, Moody, Adam T. wrote:

> Hi Chris,

Hi Adam,

> I'm interested in SLURM / OpenMPI startup numbers, but I haven't
> done this testing myself. We're stuck with an older version of
> SLURM for various internal reasons, and I'm wondering whether it's
> worth the effort to back port the PMI2 support. Can you share some
> of the differences in times at different scales?

We've not looked at startup times I'm afraid, this was time to
solution. We noticed it with Slurm when we first started using on
x86-64 for our NAMD tests (this from a posting to the list last year
when I raised the issue and were told PMI2 would be the solution):

> Slurm 2.6.0, RHEL 6.4 (latest kernel), FDR IB.
>
> Here are some timings as reported as the WallClock time by NAMD
> itself (so not including startup/tear down overhead from Slurm).
>
> srun:
>
> run1/slurm-93744.out:WallClock: 695.079773 CPUTime: 695.079773
> run4/slurm-94011.out:WallClock: 723.907959 CPUTime: 723.907959
> run5/slurm-94013.out:WallClock: 726.156799 CPUTime: 726.156799
> run6/slurm-94017.out:WallClock: 724.828918 CPUTime: 724.828918
>
> Average of 692 seconds
>
> mpirun:
>
> run2/slurm-93746.out:WallClock: 559.311035 CPUTime: 559.311035
> run3/slurm-93910.out:WallClock: 544.116333 CPUTime: 544.116333
> run7/slurm-94019.out:WallClock: 586.072693 CPUTime: 586.072693
>
> Average of 563 seconds.
>
> So that's about 23% slower.
>
> Everything is identical (they're all symlinks to the same golden
> master) *except* for the srun / mpirun which is modified by
> copying the batch script and substituting mpirun for srun.

- --
 Christopher Samuel Senior Systems Administrator
 VLSCI - Victorian Life Sciences Computation Initiative
 Email: samuel_at_[hidden] Phone: +61 (0)3 903 55545
 http://www.vlsci.org.au/ http://twitter.com/vlsci

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