Open MPI logo

Open MPI Development Mailing List Archives

  |   Home   |   Support   |   FAQ   |  

This web mail archive is frozen.

This page is part of a frozen web archive of this mailing list.

You can still navigate around this archive, but know that no new mails have been added to it since July of 2016.

Click here to be taken to the new web archives of this list; it includes all the mails that are in this frozen archive plus all new mails that have been sent to the list since it was migrated to the new archives.

Subject: Re: [OMPI devel] [OMPI svn] svn:open-mpi r17366
From: George Bosilca (bosilca_at_[hidden])
Date: 2008-02-04 13:20:00


Well, well, well ... There is really no way to make everybody happy ...

When I did the previous commit (where I added the check), Tim Prins
pointed out the following 2 paragraphs from the MPI standard.

>> MPI-1.1 s4.9.1 (p113, line 28) says the recvbuf is "significant
>> only at root".
>>
>> MPI-1.1 s2.2 (p7, line 7-9) and MPI-2 s2.3 (p7 line 1-3) have the
>> identical text:
>> "Another frequent situation arises when an argument value is needed
>> only by a subset of the processes. When an argument is not
>> significant at a process then an arbitrary value can be passed as
>> argument."

As you can see on the second paragraph, the standard claims that an
arbitrary value can be passed.

   george.

On Feb 4, 2008, at 8:17 AM, Edgar Gabriel wrote:

> George,
>
> I hate to say this, but I don't think that this is correct. Page 114
> in
> MPI 1 says (in the section about MPI_Reduce)
>
> "Thus, all processes provide input buffers and output buffers of the
> same length, with elements of the same time".
>
> The content is only significant at the root, but all processes have to
> provide the buffer according to my understanding...
>
> Thanks
> Edgar
>
> bosilca_at_[hidden] wrote:
>> Author: bosilca
>> Date: 2008-02-03 20:44:41 EST (Sun, 03 Feb 2008)
>> New Revision: 17366
>> URL: https://svn.open-mpi.org/trac/ompi/changeset/17366
>>
>> Log:
>> As the receive buffer is only significant at root, limit the
>> check only where it makes sense.
>>
>> Text files modified:
>> trunk/ompi/mpi/c/reduce.c | 4 +---
>> 1 files changed, 1 insertions(+), 3 deletions(-)
>>
>> Modified: trunk/ompi/mpi/c/reduce.c
>> =
>> =
>> =
>> =
>> =
>> =
>> =
>> =
>> =
>> =====================================================================
>> --- trunk/ompi/mpi/c/reduce.c (original)
>> +++ trunk/ompi/mpi/c/reduce.c 2008-02-03 20:44:41 EST (Sun, 03 Feb
>> 2008)
>> @@ -59,9 +59,7 @@
>> free(msg);
>> return ret;
>> } else if ((ompi_comm_rank(comm) != root && MPI_IN_PLACE ==
>> sendbuf) ||
>> - (ompi_comm_rank(comm) == root && MPI_IN_PLACE
>> == recvbuf)) {
>> - err = MPI_ERR_ARG;
>> - } else if( sendbuf == recvbuf ) {
>> + (ompi_comm_rank(comm) == root && ((MPI_IN_PLACE
>> == recvbuf) || (sendbuf == recvbuf)))) {
>> err = MPI_ERR_ARG;
>> } else {
>> OMPI_CHECK_DATATYPE_FOR_SEND(err, datatype, count);
>> _______________________________________________
>> svn mailing list
>> svn_at_[hidden]
>> http://www.open-mpi.org/mailman/listinfo.cgi/svn
>
> --
> Edgar Gabriel
> Assistant Professor
> Parallel Software Technologies Lab http://pstl.cs.uh.edu
> Department of Computer Science University of Houston
> Philip G. Hoffman Hall, Room 524 Houston, TX-77204, USA
> Tel: +1 (713) 743-3857 Fax: +1 (713) 743-3335
> _______________________________________________
> devel mailing list
> devel_at_[hidden]
> http://www.open-mpi.org/mailman/listinfo.cgi/devel



  • application/pkcs7-signature attachment: smime.p7s