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Subject: Re: [OMPI users] MPI_Test bug?
From: jody (jody.xha_at_[hidden])
Date: 2009-02-05 05:46:39


Hi Gabriele

Shouldn't you reverse the order of your send and recv from
    MPI_Irecv(buffer_recv, bufferLen, MPI_INT, recv_to, tag,
MPI_COMM_WORLD, &request);
    MPI_Send(buffer_send, bufferLen, MPI_INT, send_to, tag, MPI_COMM_WORLD);

to

    MPI_Send(buffer_send, bufferLen, MPI_INT, send_to, tag, MPI_COMM_WORLD);
    MPI_Irecv(buffer_recv, bufferLen, MPI_INT, recv_to, tag,
MPI_COMM_WORLD, &request);

?
Jody

On Thu, Feb 5, 2009 at 11:37 AM, Gabriele Fatigati <g.fatigati_at_[hidden]> wrote:
> Dear OpenMPI developer,
> i have found a very strange behaviour of MPI_Test. I'm using OpenMPI
> 1.2 over Infiniband interconnection net.
>
> I've tried to implement net check with a series of MPI_Irecv and
> MPI_Send beetwen processors, testing with MPI_Wait the end of Irecv.
> For strange reasons, i've noted that, when i launch the test in one
> node, it works well. If i launch over 2 or more procs over different
> nodes, MPI_Test fails many time before to tell that the IRecv is
> finished.
>
> I've tried that it fails also after one minutes, with very small
> buffer( less than eager limit). It's impossible that the communication
> is pending after one minutes, with 10 integer sended. To solve this,
> I need to implement a loop over MPI_Test, and only after 3 or 4
> MPI_Test it returns that IRecv finished successful. Is it possible
> that MPI_Test needs to call many time also if the communication is
> already finished?
>
> In attach you have my simple C test program.
>
> Thanks in advance.
>
> --
> Ing. Gabriele Fatigati
>
> Parallel programmer
>
> CINECA Systems & Tecnologies Department
>
> Supercomputing Group
>
> Via Magnanelli 6/3, Casalecchio di Reno (BO) Italy
>
> www.cineca.it Tel: +39 051 6171722
>
> g.fatigati [AT] cineca.it
>
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