Newsgroups: comp.parallel.mpi
From: Dick Treumann <treumann@us.ibm.com>
Subject: Re: MPI_Buffer_attach...?
Organization: IBM RS6000 SP Development
Date: Mon, 08 Jun 1998 10:49:48 -0400
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Message-ID: <357BFA0B.E5920CCC@us.ibm.com>

hamadi wrote:

> Hi all,
>
> I'm experiencing some problems with the IBM sp2 implementation of MPI.
> The problem come from the use of buffer for using with bufferized
> transmissions. More precisely, i'm attaching a local buffer for each
> process with :
> MPI_Buffer_attach(Buffer, BufferSize)
>
> At run time, the following errors occurs:
>   0:ERROR: 0032-114 Internal error:  Memory is exhausted. in MPI_Bsend,
> task 0
> This means that process 0 cannot execute more bufferized
> transmissions... That's ok.. they are too much messages.. But when i try
> to raise Buffer size with the appropriate BufferSize value there is no
> change... from small to very large values termination occurs at the same
> level in process execution...
>
> In fact i'm suspecting that the MPI implementation use a prefixed value
> for bufferized communications...
>
> Any comments, help are welcome
>
> Youssef Hamadi
> LIRMM (UM2/CNRS) France

  Youssef,

Your speculation that MPI for SP is using a fixed size buffer for MPI_Bsend
and ignoring the one you are providing is not accurate.  We use the buffer
provided by your MPI_Buffer_attach call.  If you try attaching a much
smaller buffer you will see the  error  message which applies to inadequate
MPI_Bsend buffer:

"0032-165 Out of buffer space ........

The error you are seeing may arise from too many outstanding operations but
does not have any relationship to the size of the attached Bsend buffer.


I would need more information about how you have structured your program
and how many MPI_Bsend calls you are attempting before I provide any useful
suggestions.

        Dick Treumann
  MPI Development - IBM