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Subject: Re: [OMPI users] Memchecker report on v1.3b2 (includes potential bug reports)
From: Audet, Martin (Martin.Audet_at_[hidden])
Date: 2008-11-19 14:17:19


>>>> 4) Well, this sounds reasonable, but according to the MPI-1 standard
>>>> (see page 40 for non-blocking send/recv, a more detailed explanation in
>>>> page 30):
>>>>
>>>> "A nonblocking send call indicates that the system may start copying
>>>> data out of the send buffer. The sender should */not access*/ any part
>>>> of the send buffer after a nonblocking send operation is called, until
>>>> the send completes."
>>>>
>>>> So before calling MPI_Wait to complete an isend operation, any
>>>> access to
>>>> the send buffer is illegal. It might be a little strict, but we have to
>>>> do what the standard says.
>>
>> This have been changed in the new version of the MPI standard (2.1).
>> There is no restriction anymore regarding the read operations on the
>> buffers used for non-blocking sends.
>Do you mean the next coming version of MPI standard? Because checking
>again standard 2.1 , I didn't see any changes of those paragraphs. See
>MPI Standard 2.1 (PDF version), page 52, and page 41.

The (non modifying) access to a send buffer was agreed for MPI Standard 2.2 not version 2.1 see the MPI 2.2 Wiki:

   https://svn.mpi-forum.org/trac/mpi-forum-web/wiki/MpiTwoTwoWikiPage

   https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/45

Martin