Hi there,
We are having a problem on the MPI_ALLTOALL call.
We have a code developed by somebody else, which uses
the MPI_ALLTOALL like this:
call
MPI_ALLTOALL(temp,block_c,dtype1,temp,block_c,dtype1,comm,ierr)
Note that the sending and receving buffer are the
same.
His code runs well with lam-6.5.9.
But after we upgraded our lam to version 7.0.4, the
code is giving wrong results. I am nervous that the
sending and receiving buffer are the same. I guess the
data in temp could be overwritten by new data it
receives before it can send out its own. If I change
the call to
MPI_ALLTOALL(temp,block_c,dtype1,newtemp,block_c,dtype1,comm,ierr)
It is working again.
So I guess what I am worrying is about right.
But I don't understand why the code was working
correctly with the old verion of lam. Is there any
changes in the implementation of the MPI_ALLTOALL
call?
Thank you very much.
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