[mvapich-discuss] MPI_Iallreduce() Segfault Over 512 Processes

[Hari Subramoni]

Hi Derek,

Sorry to hear that you're facing issues. Can you please try with mvapich2
2.2 and see if the failures exist?

Can you also send us the output of mpiname - a and the runtime flags (if
any) that you're using?

Thanks,
Hari.

On Sep 29, 2016 9:04 AM, "Derek Gaston" <friedmud at gmail.com> wrote:

> Hello all... I'm running into a segfault with MPI_Iallreduce().  It is
> segfaulting when using over 512 processors (yes, exactly 512.  It works at
> 512 and segfaults at 513!).
>
> It feels like MVAPICH is switching algorithms or something... and the one
> it's switching too isn't happy!
>
> I'm on an SGI ICE-X cluster with Mellanox ConnectX-3 ( MT27500 Family)
> FDR Infiniband cards.
>
> My test application is down at the bottom of this email.  Using it I've
> found that MVAPICH2/2.0.1 and MVAPICH2/2.1 both segfault...
> while MVAPICH2/1.9 does NOT.  I haven't tried 2.2 yet, but I'll try to do
> that tomorrow.
>
> Any advice?  Maybe there's a compile switch we missed or a runtime option
> I should try?
>
> Thanks for any help!
>
> Derek
>
>
> #include <mpi.h>
>
>
>
>
>
> int main(int argc, char** argv)
>
>
> {
>
>
>   MPI_Init(&argc, &argv);
>
>
>
>
>
>   double r = 1.2;
>
>
>   double o;
>
>
>
>
>
>   MPI_Request req;
>
>
>   MPI_Status  stat;
>
>
>
>
>
>   MPI_Iallreduce (&r, &o, 1, MPI_DOUBLE, MPI_SUM, MPI_COMM_WORLD, &req);
>
>
>
>
>
>   MPI_Wait(&req, &stat);
>
>
>
>
>
>   MPI_Finalize();
>
>
> }
>
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>
>
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