--- /dev/null
+ /* Short or medium size message and power-of-two no. of processes. Use
+ * recursive doubling algorithm */
+#include "colls_private.h"
+#define MPIR_ALLGATHERV_TAG 222
+int smpi_coll_tuned_allgatherv_mpich_rdb (
+ void *sendbuf,
+ int sendcount,
+ MPI_Datatype sendtype,
+ void *recvbuf,
+ int *recvcounts,
+ int *displs,
+ MPI_Datatype recvtype,
+ MPI_Comm comm)
+{
+ int comm_size, rank, j, i;
+ MPI_Status status;
+ MPI_Aint recvtype_extent, recvtype_true_extent, recvtype_true_lb;
+ int curr_cnt, dst, total_count;
+ void *tmp_buf;
+ int mask, dst_tree_root, my_tree_root, is_homogeneous, position,
+ send_offset, recv_offset, last_recv_cnt=0, nprocs_completed, k,
+ offset, tmp_mask, tree_root;
+
+ comm_size = smpi_comm_size(comm);
+ rank = smpi_comm_rank(comm);
+
+ total_count = 0;
+ for (i=0; i<comm_size; i++)
+ total_count += recvcounts[i];
+
+ if (total_count == 0) return MPI_ERR_COUNT;
+
+ recvtype_extent=smpi_datatype_get_extent( recvtype);
+
+ is_homogeneous = 1;
+
+ if (is_homogeneous) {
+ /* need to receive contiguously into tmp_buf because
+ displs could make the recvbuf noncontiguous */
+
+ smpi_datatype_extent(recvtype, &recvtype_true_lb, &recvtype_true_extent);
+
+ tmp_buf= (void*)xbt_malloc(total_count*(max(recvtype_true_extent,recvtype_extent)));
+
+ /* adjust for potential negative lower bound in datatype */
+ tmp_buf = (void *)((char*)tmp_buf - recvtype_true_lb);
+
+ /* copy local data into right location in tmp_buf */
+ position = 0;
+ for (i=0; i<rank; i++) position += recvcounts[i];
+ if (sendbuf != MPI_IN_PLACE)
+ {
+ smpi_datatype_copy(sendbuf, sendcount, sendtype,
+ ((char *)tmp_buf + position*
+ recvtype_extent),
+ recvcounts[rank], recvtype);
+ }
+ else
+ {
+ /* if in_place specified, local data is found in recvbuf */
+ smpi_datatype_copy(((char *)recvbuf +
+ displs[rank]*recvtype_extent),
+ recvcounts[rank], recvtype,
+ ((char *)tmp_buf + position*
+ recvtype_extent),
+ recvcounts[rank], recvtype);
+ }
+ curr_cnt = recvcounts[rank];
+
+ mask = 0x1;
+ i = 0;
+ while (mask < comm_size) {
+ dst = rank ^ mask;
+
+ /* find offset into send and recv buffers. zero out
+ the least significant "i" bits of rank and dst to
+ find root of src and dst subtrees. Use ranks of
+ roots as index to send from and recv into buffer */
+
+ dst_tree_root = dst >> i;
+ dst_tree_root <<= i;
+
+ my_tree_root = rank >> i;
+ my_tree_root <<= i;
+
+ if (dst < comm_size) {
+ send_offset = 0;
+ for (j=0; j<my_tree_root; j++)
+ send_offset += recvcounts[j];
+
+ recv_offset = 0;
+ for (j=0; j<dst_tree_root; j++)
+ recv_offset += recvcounts[j];
+
+ smpi_mpi_sendrecv(((char *)tmp_buf + send_offset * recvtype_extent),
+ curr_cnt, recvtype, dst,
+ MPIR_ALLGATHERV_TAG,
+ ((char *)tmp_buf + recv_offset * recvtype_extent),
+ total_count - recv_offset, recvtype, dst,
+ MPIR_ALLGATHERV_TAG,
+ comm, &status);
+ /* for convenience, recv is posted for a bigger amount
+ than will be sent */
+ last_recv_cnt=smpi_mpi_get_count(&status, recvtype);
+ curr_cnt += last_recv_cnt;
+ }
+
+ /* if some processes in this process's subtree in this step
+ did not have any destination process to communicate with
+ because of non-power-of-two, we need to send them the
+ data that they would normally have received from those
+ processes. That is, the haves in this subtree must send to
+ the havenots. We use a logarithmic
+ recursive-halfing algorithm for this. */
+
+ /* This part of the code will not currently be
+ executed because we are not using recursive
+ doubling for non power of two. Mark it as experimental
+ so that it doesn't show up as red in the coverage
+ tests. */
+
+ /* --BEGIN EXPERIMENTAL-- */
+ if (dst_tree_root + mask > comm_size) {
+ nprocs_completed = comm_size - my_tree_root - mask;
+ /* nprocs_completed is the number of processes in this
+ subtree that have all the data. Send data to others
+ in a tree fashion. First find root of current tree
+ that is being divided into two. k is the number of
+ least-significant bits in this process's rank that
+ must be zeroed out to find the rank of the root */
+ j = mask;
+ k = 0;
+ while (j) {
+ j >>= 1;
+ k++;
+ }
+ k--;
+
+ tmp_mask = mask >> 1;
+
+ while (tmp_mask) {
+ dst = rank ^ tmp_mask;
+
+ tree_root = rank >> k;
+ tree_root <<= k;
+
+ /* send only if this proc has data and destination
+ doesn't have data. at any step, multiple processes
+ can send if they have the data */
+ if ((dst > rank) &&
+ (rank < tree_root + nprocs_completed)
+ && (dst >= tree_root + nprocs_completed)) {
+
+ offset = 0;
+ for (j=0; j<(my_tree_root+mask); j++)
+ offset += recvcounts[j];
+ offset *= recvtype_extent;
+
+ smpi_mpi_send(((char *)tmp_buf + offset),
+ last_recv_cnt,
+ recvtype, dst,
+ MPIR_ALLGATHERV_TAG, comm);
+ /* last_recv_cnt was set in the previous
+ receive. that's the amount of data to be
+ sent now. */
+ }
+ /* recv only if this proc. doesn't have data and sender
+ has data */
+ else if ((dst < rank) &&
+ (dst < tree_root + nprocs_completed) &&
+ (rank >= tree_root + nprocs_completed)) {
+
+ offset = 0;
+ for (j=0; j<(my_tree_root+mask); j++)
+ offset += recvcounts[j];
+
+ smpi_mpi_recv(((char *)tmp_buf + offset * recvtype_extent),
+ total_count - offset, recvtype,
+ dst, MPIR_ALLGATHERV_TAG,
+ comm, &status);
+ /* for convenience, recv is posted for a
+ bigger amount than will be sent */
+ last_recv_cnt=smpi_mpi_get_count(&status, recvtype);
+ curr_cnt += last_recv_cnt;
+ }
+ tmp_mask >>= 1;
+ k--;
+ }
+ }
+ /* --END EXPERIMENTAL-- */
+
+ mask <<= 1;
+ i++;
+ }
+
+ /* copy data from tmp_buf to recvbuf */
+ position = 0;
+ for (j=0; j<comm_size; j++) {
+ if ((sendbuf != MPI_IN_PLACE) || (j != rank)) {
+ /* not necessary to copy if in_place and
+ j==rank. otherwise copy. */
+ smpi_datatype_copy(((char *)tmp_buf + position*recvtype_extent),
+ recvcounts[j], recvtype,
+ ((char *)recvbuf + displs[j]*recvtype_extent),
+ recvcounts[j], recvtype);
+ }
+ position += recvcounts[j];
+ }
+ }
+return MPI_SUCCESS;
+}
