Thank you Gilles, the *&data* was the problem.
On Thu, Nov 30, 2017 at 2:25 AM, Gilles Gouaillardet <gil...@rist.or.jp> wrote: > should the send buffer for MPI_Allgatherv() be data instead of &data ? > > BTW, is this issue specific to Open MPI ? > If this is a general MPI issue, forums such as https://stackoverflow.com > are a better place for this. > > Cheers, > > Gilles > > On 11/30/2017 5:02 PM, Konstantinos Konstantinidis wrote: > >> Hi, I will use a small part of C++ code to demonstrate my problem during >> shuffling. Assume that each slave has to shuffle some unsigned char array >> defined as *unsigned char* data *within some intracommunicator. >> >> *unsigned lineSize = 100;* >> *unsigned long long no_keys = 10;* >> *int bytes_send_count = (int)no_keys*lineSize; * >> *unsigned int commSize = (unsigned)comm.Get_size();* >> *int* recv_counts = new int[commSize];* >> *int* displs = new int[commSize];* >> * >> * >> *//Shuffle amount of data* >> *comm.Allgather(&bytes_send_count, 1, MPI::INT, recv_counts, 1, >> MPI::INT); * >> * >> * >> *unsigned long long total = 0; * >> *for(unsigned int i = 0; i < commSize; i++){* >> *//Update the displacements* >> *displs[i] = total; * >> ** >> *//...and the total count* >> *total += recv_counts[i]; * >> *}* >> * >> * >> *unsigned char* recv_buf = new unsigned char[total]; >> * >> * >> * >> *//Print data to be sent from rank == 1* >> *if(rank == 1){* >> *for(int l=0; l<bytes_send_count;l++){* >> *printf("%d: Data to be sent is %d\n", rank, data[l]);* >> *}* >> *}* >> * >> * >> *//Shuffle actual data* >> *comm.Allgatherv(&data, bytes_send_count, MPI::UNSIGNED_CHAR, recv_buf, >> recv_counts, displs, MPI::UNSIGNED_CHAR);* >> * >> * >> *//Check the first portion of the received data* >> *if(rank == 1){* >> *for(int l=0; l<recv_counts[0]; l++){* >> *printf("%d: Data received from myself is %d\n", rank, recv_buf[l]);* >> *}* >> *}* >> * >> * >> My problem is that the printf() that checks what is about to be sent from >> node 1 and what is actually received from node 1 by itself print different >> things that don't match. Based on my study of Allgatherv() I think that the >> sizes of the received blocks and the displacements are computed correctly. >> I don't think I need MPI_IN_PLACE since the input and output buffers are >> supposed to be different. >> >> Can you help me identify the problem? >> >> I am using Open MPI 2.1.2 and testing on a single computer with 7 MPI >> processes. The ompi_info is the attached file. >> >> >> _______________________________________________ >> users mailing list >> users@lists.open-mpi.org >> https://lists.open-mpi.org/mailman/listinfo/users >> > > _______________________________________________ > users mailing list > users@lists.open-mpi.org > https://lists.open-mpi.org/mailman/listinfo/users
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