Re: Gadget stalling without apparent reason

From: Christian Wagner <>
Date: Wed, 07 Sep 2011 02:03:09 +0200

Hi Enrique,

I had a very similar problem with our cluster.
In my case, it was a problem with the InfiniBand communication. The
following mpiexec options solved the problem for me:

-mca mpi_leave_pinned 0 -mca btl_openib_eager_rdma 0

It's worth a try.

Cheers, Christian

On 09/07/2011 01:34 AM, Enrique Vazquez wrote:
> Hi,
> I'm submitting some test runs on my new 180-core cluster, but I'm
> encountering a very strange behavior: a run that I had performed in
> my previous cluster (118^3 SPH particles, no DM particles, on 8 CPUs),
> with identical parameters, and only the compile options being different
> to fit the new system, runs fine on 8 cores, but when I run it run on 32
> cores, it only advances up to a certain time, and then ceases to advance any
> further. It generally stops somewhere near the tree calculation, either
> while doing the domain decomposition, or while computing the tree force,
> or while computing the potential for all particles. Other runs I'm doing
> with larger SPH particle numbers (up to 27 million) on up to 128 cores
> act the same way.
> The strange part is that there's no crash. The system behaves as if it
> had entered an infinite loop, with the processors still crunching at full
> speed, but no further advance in simulation time occurs. No error messages
> are displayed, and the last timestep printed is perfectly normal (0.146).
> Because the problem occurs for 32 cores but not for 8, I guess it's some
> problem with MPI.
> I'm running Gadget2, with a few modifications by us to include extra ISM physics,
> on AMD 12-core processors, using OpenMPI and Intel compilers. The connectivity
> is Infiniband. Any suggestions or insight will be greatly appreciated!
> Best regards,
> Enrique
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Received on 2011-09-07 02:35:17

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