[mvapich-discuss] mvapich2 1.7rc1 and 2GB transfers

[Gus Correa]

Hi Tibor

This problem seems to happen in all MPIs.
'count' is an int, your array must be <2GB.
Larger values will probably be folded into negative numbers,
hence the error you see.
A known workaround for larger data transfers
is to define an MPI type (say MPI_Type_Contiguous or MPI_Type_Vector)
for array segments <2GB, and transfer several segments at once
using that type instead of the MPI native types.

I hope this helps,
Gus Correa

Tibor Pausz wrote:
> Hi there
> 
> I have installed mvapich2 1.7rc1 with this configure options
> ./configure --enable-fc --enable-cxx --with-hwloc
> --with-slurm=.../slurm/2.2.7 --with-rdma=gen2 --enable-shared
> --enable-sharedlibs=gcc --with-xrc
> Compiler Intel 11.1, Scientific Linux 5.5
> 
> Now im trying to transfer with MPI_Ssend arrays which are larger than
> 2GB, and a got the following message.
> Warning! Rndv Receiver is expecting 0 Bytes But, is receiving 0 Bytes
> 
> After that the program just hangs. I have tried "int" and "long" as type
> of argument "count". But I have allways the same warning.
> 
> Best regards,
> Tibor
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