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Subject: Re: [OMPI users] MPI_Test bug?
From: Gabriele Fatigati (g.fatigati_at_[hidden])
Date: 2009-02-05 05:48:34


Hi Jody,
thanks four your quick reply. But what's the difference?

2009/2/5 jody <jody.xha_at_[hidden]>:
> 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
>>
>> _______________________________________________
>> users mailing list
>> users_at_[hidden]
>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>
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>

-- 
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