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From: George Bosilca (bosilca_at_[hidden])
Date: 2007-08-01 11:56:14


Juan,

I have to check to see what's wrong there. We build Open MPI with
full support for data transfer up to sizeof(size_t) bytes. so you
case should be covered. However, there are some known problems with
the MPI interface for data larger than sizeof(int). As an example the
_count field in the MPI_Status structure will be truncated ...

   Thanks,
     george.

On Jul 30, 2007, at 1:47 AM, Juan Carlos Guzman wrote:

> Hi,
>
> Does anyone know the maximum buffer size I can use in MPI_Send()
> (MPI_Recv) function?. I was doing some testing using two nodes on my
> cluster to measure the point-to-point MPI message rate depending on
> size. The test program exchanges MPI_FLOAT datatypes between two
> nodes. I was able to send up to 4 GB of data (500 Mega MPI_FLOATs)
> before the process crashed with a segmentation fault message.
>
> Is the maximum size of the message limited by the sizeof(int) * sizeof
> (MPI data type) used in the MPI_Send()/MPI_Recv() functions?
>
> My cluster has openmpi 1.2.3 installed. Each node has 2 x dual core
> AMD Opteron and 12 GB RAM.
>
> Thanks in advance.
> Juan-Carlos.
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