+void smpi_mpi_gatherv(void *sendbuf, int sendcount, MPI_Datatype sendtype,
+ void *recvbuf, int *recvcounts, int *displs,
+ MPI_Datatype recvtype, int root, MPI_Comm comm)
+{
+ int system_tag = 666;
+ int rank, size, src, index;
+ MPI_Aint lb = 0, recvext = 0;
+ MPI_Request *requests;
+
+ rank = smpi_comm_rank(comm);
+ size = smpi_comm_size(comm);
+ if(rank != root) {
+ // Send buffer to root
+ smpi_mpi_send(sendbuf, sendcount, sendtype, root, system_tag, comm);
+ } else {
+ // FIXME: check for errors
+ smpi_datatype_extent(recvtype, &lb, &recvext);
+ // Local copy from root
+ smpi_datatype_copy(sendbuf, sendcount, sendtype,
+ (char *)recvbuf + displs[root] * recvext,
+ recvcounts[root], recvtype);
+ // Receive buffers from senders
+ requests = xbt_new(MPI_Request, size - 1);
+ index = 0;
+ for(src = 0; src < size; src++) {
+ if(src != root) {
+ requests[index] =
+ smpi_irecv_init((char *)recvbuf + displs[src] * recvext,
+ recvcounts[src], recvtype, src, system_tag, comm);
+ index++;
+ }
+ }
+ // Wait for completion of irecv's.
+ smpi_mpi_startall(size - 1, requests);
+ smpi_mpi_waitall(size - 1, requests, MPI_STATUS_IGNORE);
+ xbt_free(requests);
+ }