I get the sender's rank in status.MPI_SOURCE, but it is different than expected. I need to receive that message which was sent to me, not any message. 

regards,

Date: Fri, 15 Jul 2011 06:33:41 -0400
From: Terry Dontje <terry.dontje@oracle.com>
Subject: Re: [OMPI users] Urgent Question regarding, MPI_ANY_SOURCE.
To: users@open-mpi.org
Message-ID: <4E201785.6010101@oracle.com>
Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"

Mudassar,

You can do what you are asking.  The receiver uses MPI_ANY_SOURCE for
the source rank value and when you receive a message the
status.MPI_SOURCE will contain the rank of the actual sender not the
receiver's rank.  If you are not seeing that then there is a bug somewhere.

--td

On 7/14/2011 9:54 PM, Mudassar Majeed wrote:
> Friend,
>              I can not specify the rank of the sender. Because only
> the sender knows to which receiver the message is to be sent. The
> receiver does not know from which sender the message will come. I am
> trying to do a research work on load balancing in MPI application
> where load is redistributed, so in that I require a receiver to
> receive a load value from a sender that it does not know. On the other
> hand, the sender actually calculates, to which receiver this load
> value should be sent. So for this, I want sender to send a message
> containing the load to a receiver, but receiver does not know from
> which sender the message will come. See, it is like send receiver in
> DATAGRAM sockets. The receiver, receives the message on the IP and
> port, the message which was directed for it. I want to have same
> behavior. But it seems that it is not possible in MPI. Isn't it?
>
> regards,
> Mudassar
>
> ------------------------------------------------------------------------
> *From:* Jeff Squyres <jsquyres@cisco.com>
> *To:* Mudassar Majeed <mudassarm30@yahoo.com>
> *Cc:* Open MPI Users <users@open-mpi.org>
> *Sent:* Friday, July 15, 2011 3:30 AM
> *Subject:* Re: [OMPI users] Urgent Question regarding, MPI_ANY_SOURCE.
>
> Right.  I thought you were asking about receiving *another* message
> from whomever you just received from via ANY_SOURCE.
>
> If you want to receive from a specific sender, you just specify the
> rank you want to receive from -- not ANY_SOURCE.
>
> You will always only receive messages that were sent to *you*. 
> There's no MPI_SEND_TO_ANYONE_WHO_IS_LISTENING functionality, for
> example.  So your last statement: "But when it captures with ..
> MPI_ANY_SOURCE and MPI_ANY_TAG, the receiver will capture any message
> (even not targetted for it)" is incorrect.
>
> I guess I still don't understand your question...?
>
>
> On Jul 14, 2011, at 9:17 PM, Mudassar Majeed wrote:
>
> >
> > I know this, but when I compare status.MPI_SOURCE with myid, they
> are different. I guess you need to reconsider my question. The
> MPI_Recv function seems to capture message from the queue with some
> search parameters like source, tag etc. So in case the receiver does
> not know the sender and wants to receive only that message which was
> sent for this receiver. But when it captures with source as
> MPI_ANY_SOURCE and MPI_ANY_TAG, the receiver will capture any message
> (even not targetted for it).
> >
> > regards,
> > Mudassar
> >
> >
> > From: Jeff Squyres <jsquyres@cisco.com <mailto:jsquyres@cisco.com>>
> > To: Mudassar Majeed <mudassarm30@yahoo.com
> <mailto:mudassarm30@yahoo.com>>; Open MPI Users <users@open-mpi.org
> <mailto:users@open-mpi.org>>
> > Sent: Friday, July 15, 2011 1:58 AM
> > Subject: Re: [OMPI users] Urgent Question regarding, MPI_ANY_SOURCE.
> >
> > When you use MPI_ANY_SOURCE in a receive, the rank of the actual
> sender is passed back to you in the status.MPI_SOURCE.
> >
> > On Jul 14, 2011, at 7:55 PM, Mudassar Majeed wrote:
> >
> > > Hello people,
> > >                        I am trapped in the following problem plz
> help me. Suppose a process A sends a message to process B. The process
> B will receive the message with MPI_Recv with MPI_ANY_SOURCE in the
> source argument. Let say process B does not know that A is the sender.
> But I want B to receive message from process A (the one who actually
> sends the message to process B). But if I use MPI_ANY_SOURCE, then any
> message from any source is captured by process B (let say there are
> other processes sending messages). Instead of MPI_ANY_SOURCE I cannot
> use A in the source argument as B does not know about the sender. What
> should I do in this situation ?
> > >
> > > regards,
> > > Mudassar Majeed
> > > _______________________________________________
> > > users mailing list
> > > users@open-mpi.org <mailto:users@open-mpi.org>
> > > http://www.open-mpi.org/mailman/listinfo.cgi/users
> >
> >
> > --
> > Jeff Squyres
> > jsquyres@cisco.com <mailto:jsquyres@cisco.com>
> > For corporate legal information go to:
> > http://www.cisco.com/web/about/doing_business/legal/cri/
> >
> >
> >
>
>
> --
> Jeff Squyres
> jsquyres@cisco.com <mailto:jsquyres@cisco.com>
> For corporate legal information go to:
> http://www.cisco.com/web/about/doing_business/legal/cri/
>
>
>
>
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