Newsgroups: comp.parallel.mpi
From: gmounie@ens-lyon.fr (Gregory Mounie)
Subject: Re: Overlapping send and receive buffers in coll
Organization: Ecole Normale Superieure de Lyon, France
Date: 4 Nov 1994 14:25:31 GMT
Message-ID: <39dg8r$9qk@cri.ens-lyon.fr>

In article 2g5@lll-winken.llnl.gov, neely@crevasse.llnl.gov (Rob Neely) writes:
> Is it legal to do "in place" gathering using the gather/gatherv
> functions?   That is, I want my send buffer to overlap with my receive
> buffer on the root node.
...
> Is this allowed?  All of the examples I've seen use separate send and
> receive buffers, but the standard does not explicitly say (at least that
> I can find).  
> 
> Thanks.
> 
> --Rob Neely, LLNL
> --rneely@llnl.gov

I think the standart explicitely says that it is not allowed. If i remember
rightly, it's in the beginning of the MPI-draft, somewhere in the discussion about
 buffer.

I suppose the limitation came from calls of memory copy. Strange copy occur on some 
 computer when the source and the destination memories are overlapping.

 Gregory




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