Re: Fw: [bgl-discuss] MPI failure, simplified

[Stephen Siegel <siegel@xxxxxxxxxxxx>]

On Sat, 6 May 2006, Rajeev Thakur wrote:

> I was looking up something else in the MPI Standard when I came across this
> example under "Semantics of point-to-point communication". Example 3.7, pg
> 32, MPI-1.1.
> It says:
> 
> "Example 3.7 An exchange of messages.
> 
> CALL MPI_COMM_RANK(comm, rank, ierr) 
> IF (rank.EQ.0) THEN 
>     CALL MPI_SEND(sendbuf, count, MPI_REAL, 1, tag, comm, ierr) 
>     CALL MPI_RECV(recvbuf, count, MPI_REAL, 1, tag, comm, status, ierr) 
> ELSE    ! rank.EQ.1 
>     CALL MPI_RECV(recvbuf, count, MPI_REAL, 0, tag, comm, status, ierr) 
>     CALL MPI_SEND(sendbuf, count, MPI_REAL, 0, tag, comm, ierr) 
> END IF 
> 
> This program will succeed even if no buffer space for data is available." 
> 
> 
> Note that it does not put any restriction on the size of the sendbuf. It
> says the program will succeed even if there is no buffer space available.
> 
> Going by this, I would say that the Standard says that Steve's code should
> work.

I agree! (But can anyone convince IBM?)  -Steve

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