Can you write this up in a small, complete program that shows the problem, and
that we can compile and run?
On Jul 15, 2011, at 3:36 PM, Mudassar Majeed wrote:
> *id is same as myid
>
> I am comparing the results by seeing the printed messages, given by the
> printfs....
>
> the recv_packet.rank is the rank of the sender that should be equal to
> status.MPI_SOURCE but it is not.
>
> I have updated the code a little bit, here is it.
>
> if( (is_receiver == 1) && (is_sender != 1) )
> {
> printf("\nP%d >> Receiver only ...!!", myid);
> printf("\n");
> MPI_Recv(&recv_packet, 1, loadDatatype, MPI_ANY_SOURCE, MPI_TAG_LOAD,
> comm, &status);
> printf("\nP%d >> Received from P%d, packet contains rank: %d", myid,
> status.MPI_SOURCE, recv_packet.rank);
> printf("\n");
> }
> else if( (is_sender == 1) && (is_receiver != 1) )
> {
> load_packet.rank = myid;
> load_packet.ld = load;
> printf("\nP%d >> Sender only ...!! P%d", myid, rec_rank);
> printf("\n");
> MPI_Ssend(&load_packet, 1, loadDatatype, rec_rank, MPI_TAG_LOAD,
> comm);
> }
> else if( (is_receiver == 1) && (is_sender == 1) )
> {
> load_packet.rank = myid;
> load_packet.ld = load;
> printf("\nP%d >> Both ...!! P%d", myid, rec_rank);
> printf("\n");
> MPI_Sendrecv(&load_packet, 1, loadDatatype, rec_rank, MPI_TAG_LOAD,
> &recv_packet, 1, loadDatatype, MPI_ANY_SOURCE, MPI_TAG_LOAD,
> comm, &status);
> printf("\nP%d >> Received from P%d, packet contains rank: %d", myid,
> status.MPI_SOURCE, recv_packet.rank);
> printf("\n");
> }
>
> here is the output
>
> P11 >> Sender only ...!! P2
>
> P14 >> Sender only ...!! P6
>
> P15 >> Neither ...!!
>
> P15 >> I could reach here ...!!
>
> P8 >> Neither ...!!
>
> P8 >> I could reach here ...!!
>
> P1 >> Receiver only ...!!
>
> P9 >> Sender only ...!! P0
>
> P2 >> Receiver only ...!!
>
>
> P10 >> Sender only ...!! P1
>
> P3 >> Receiver only ...!!
>
> P3 >> Received from P13, packet contains rank: 14
>
>
> P0 >> Receiver only ...!!
>
> P0 >> Received from P3, packet contains rank: 9
>
> P4 >> Receiver only ...!!
>
> P12 >> Neither ...!!
>
> P12 >> I could reach here ...!!
>
> P5 >> Both ...!! P3
>
> P13 >> Sender only ...!! P4
>
> P13 >> I could reach here ...!!
>
> P6 >> Both ...!! P5
>
> P7 >> Neither ...!!
>
> P7 >> I could reach here ...!!
>
> P14 >> I could reach here ...!!
>
> P1 >> Received from P7, packet contains rank: 11
>
> P1 >> I could reach here ...!!
>
> P9 >> I could reach here ...!!
> P2 >> Received from P11, packet contains rank: 13
>
> P2 >> I could reach here ...!!
>
> P0 >> I could reach here ...!!
>
> P11 >> I could reach here ...!!
> P3 >> I could reach here ...!!
>
>
> regards,
> Mudassar
>
> From: Terry Dontje <[email protected]>
> To: Mudassar Majeed <[email protected]>
> Cc: "[email protected]" <[email protected]>
> Sent: Friday, July 15, 2011 9:06 PM
> Subject: Re: [OMPI users] Urgent Question regarding, MPI_ANY_SOURCE.
>
>
>
> On 7/15/2011 2:35 PM, Mudassar Majeed wrote:
>>
>> Here is the code
>>
>> if( (is_receiver == 1) && (is_sender != 1) )
>> {
>> printf("\nP%d >> Receiver only ...!!", myid);
>> printf("\n");
>> MPI_Recv(&recv_packet, 1, loadDatatype, MPI_ANY_SOURCE,
>> MPI_TAG_LOAD, comm, &status);
>> printf("\nP%d >> Received from P%d", myid, status.MPI_SOURCE);
>> printf("\n");
>> }
>> else if( (is_sender == 1) && (is_receiver != 1) )
>> {
>> load_packet.rank = *id;
>> load_packet.ld = load;
>> printf("\nP%d >> Sender only ...!! P%d", myid, rec_rank);
>> printf("\n");
>> MPI_Ssend(&load_packet, 1, loadDatatype, rec_rank, MPI_TAG_LOAD,
>> comm);
>> }
>> else if( (is_receiver == 1) && (is_sender == 1) )
>> {
>> load_packet.rank = *id;
>> load_packet.ld = load;
>> printf("\nP%d >> Both ...!! P%d", myid, rec_rank);
>> printf("\n");
>> MPI_Sendrecv(&load_packet, 1, loadDatatype, rec_rank, MPI_TAG_LOAD,
>> &recv_packet, 1, loadDatatype, MPI_ANY_SOURCE, MPI_TAG_LOAD,
>> comm, &status);
>> printf("\nP%d >> Received from P%d", myid, status.MPI_SOURCE);
>> printf("\n");
>> }
>>
>> A process can be a message sender, or receiver or both. There are 16 ranks.
>> "rec_rank" contains the rank of the receiver. It is displayed before the
>> message is sent.
>> Every sender displays this "rec_rank" and it should correctly. But on the
>> receiver sides, status.MPI_SOURCE is displayed (after receiving message),
>> but the value
>> is not matching with the expected sender's rank.
> Sorry, but I still don't see how you are detecting the mismatch. I assume
> load_packet_rank some how relates to load_packet. But why are you setting it
> to *id instead of myid? Also on the receive side I see no place where you
> pull out the rank from the recv_packet to compare with status.MPI_SOURCE.
>>
>> I did not understand about kernel that you were talking about.
>>
> A "kernel" that I am talking about is a small piece of code someone can build
> and run to see the problem.
>> See the code is very clear and it sends the message to "rec_rank" that was
>> displayed before sending the message. But on the receiver side the
>> MPI_SOURCE comes to be wrong.
>> This shows to me that messages on the receiving sides are captured on the
>> basis of MPI_ANY_SOURCE, that seems like it does not see the destination of
>> message while capturing it from message queue of the MPI system.
>>
>> regards,
>> Mudassar
>>
>> From: Terry Dontje <[email protected]>
>> To: Mudassar Majeed <[email protected]>
>> Cc: "[email protected]" <[email protected]>
>> Sent: Friday, July 15, 2011 7:10 PM
>> Subject: Re: [OMPI users] Urgent Question regarding, MPI_ANY_SOURCE.
>>
>>
>>
>> On 7/15/2011 12:49 PM, Mudassar Majeed wrote:
>>>
>>> Yes, processes receive messages that were not sent to them. I am receiving
>>> the message with the following call
>>>
>>> MPI_Recv(&recv_packet, 1, loadDatatype, MPI_ANY_SOURCE, MPI_TAG_LOAD, comm,
>>> &status);
>>>
>>> and that was sent using the following call,
>>>
>>> MPI_Ssend(&load_packet, 1, loadDatatype, rec_rank, MPI_TAG_LOAD, comm);
>>>
>>> What problem it can have ?. All the parameters are correct, I have seen
>>> them by printf. What I am thinking is that, the receive is done with
>>> MPI_ANY_SOURCE, so the process is getting any message (from any source).
>>> What should be done so that only that message is captured that had the
>>> destination as this process.
>>>
>> By virtue of MPI the MPI_Recv call should only return messages destined for
>> that rank. What makes you think that is not happening? Can you make some
>> sort of kernel of code that proves your theory that your MPI_Recv is
>> receiving another rank's message? If you can and then post that code maybe
>> we'll be able to figure out what the issue is.
>>
>> Right now, it seems we are at a deadlock of you claiming something is
>> happening that really cannot be happening. So unless we have more than a
>> broad description of the problem it is going to be nearly impossible for us
>> to tell you what is wrong.
>>
>> --td
>>> regards,
>>> Mudassar
>>>
>>> Date: Fri, 15 Jul 2011 07:04:34 -0400
>>> From: Terry Dontje <[email protected]>
>>> Subject: Re: [OMPI users] Urgent Question regarding, MPI_ANY_SOURCE.
>>> To: [email protected]
>>> Message-ID: <[email protected]>
>>> Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
>>>
>>> Well MPI_Recv does give you the message that was sent specifically to
>>> the rank calling it by any of the processes in the communicator. If you
>>> think the message you received should have gone to another rank then
>>> there is a bug somewhere. I would start by either adding debugging
>>> printf's to your code to trace the messages. Or narrowing down the
>>> code to a small kernel such that you can prove to yourself that MPI is
>>> working the way it should and if not you can show us where it is going
>>> wrong.
>>>
>>> --td
>>>
>>> On 7/15/2011 6:51 AM, Mudassar Majeed wrote:
>>> > 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 <[email protected]
>>> > <mailto:[email protected]>>
>>> > Subject: Re: [OMPI users] Urgent Question regarding, MPI_ANY_SOURCE.
>>> > To: [email protected] <mailto:[email protected]>
>>> > Message-ID: <[email protected]
>>> > <mailto:[email protected]>>
>>> > 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 <[email protected] <mailto:[email protected]>>
>>> > > *To:* Mudassar Majeed <[email protected]
>>> > <mailto:[email protected]>>
>>> > > *Cc:* Open MPI Users <[email protected] <mailto:[email protected]>>
>>> > > *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 <[email protected] <mailto:[email protected]>
>>> > <mailto:[email protected] <mailto:[email protected]>>>
>>> > > > To: Mudassar Majeed <[email protected]
>>> > <mailto:[email protected]>
>>> > > <mailto:[email protected] <mailto:[email protected]>>>; Open
>>> > MPI Users <[email protected] <mailto:[email protected]>
>>> > > <mailto:[email protected] <mailto:[email protected]>>>
>>> > > > 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
>>
>> --
>> <Mail Attachment.gif>
>> Terry D. Dontje | Principal Software Engineer
>> Developer Tools Engineering | +1.781.442.2631
>> Oracle - Performance Technologies
>> 95 Network Drive, Burlington, MA 01803
>> Email [email protected]
>>
>>
>>
>>
>>
>
> --
> <Mail Attachment.gif>
> Terry D. Dontje | Principal Software Engineer
> Developer Tools Engineering | +1.781.442.2631
> Oracle - Performance Technologies
> 95 Network Drive, Burlington, MA 01803
> Email [email protected]
>
>
>
>
>
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--
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[email protected]
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