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From: Jelena Pjesivac-Grbovic (pjesa_at_[hidden])
Date: 2007-08-01 12:42:25


it is possible that the problem is not in MPI - I've seen similar problem
on some of our workstations some time ago.
Juan, are you sure you can allocate more than 2x 4GB memory of data in
non-mpi program on your system?


On Wed, 1 Aug 2007, George Bosilca wrote:

> 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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Jelena Pjesivac-Grbovic, Pjesa
Graduate Research Assistant
Innovative Computing Laboratory
Computer Science Department, UTK
Claxton Complex 350
(865) 974 - 6722 
(865) 974 - 6321
"The only difference between a problem and a solution is that
  people understand the solution."
                                       -- Charles Kettering