--- /dev/null
+/* Copyright (c) 2013-2014. The SimGrid Team.
+ * All rights reserved. */
+
+/* This program is free software; you can redistribute it and/or modify it
+ * under the terms of the license (GNU LGPL) which comes with this package. */
+
+#include "colls_private.h"
+/* IMPLEMENTED BY PITCH PATARASUK
+ Non-topoloty-specific (however, number of cores/node need to be changed)
+ all-reduce operation designed for smp clusters
+ It uses 2-layer communication: binomial for intra-communication
+ and rdb for inter-communication*/
+
+
+/* ** NOTE **
+ Use -DMPICH2 if this code does not compile.
+ MPICH1 code also work on MPICH2 on our cluster and the performance are similar.
+ This code assume commutative and associative reduce operator (MPI_SUM, MPI_MAX, etc).
+*/
+
+//#include <star-reduction.c>
+
+/*
+This fucntion performs all-reduce operation as follow.
+1) binomial_tree reduce inside each SMP node
+2) Recursive doubling intra-communication between root of each SMP node
+3) binomial_tree bcast inside each SMP node
+*/
+int smpi_coll_tuned_allreduce_smp_rdb(void *send_buf, void *recv_buf, int count,
+ MPI_Datatype dtype, MPI_Op op,
+ MPI_Comm comm)
+{
+ int comm_size, rank;
+ void *tmp_buf;
+ int tag = COLL_TAG_ALLREDUCE;
+ int mask, src, dst;
+ MPI_Status status;
+ if(smpi_comm_get_leaders_comm(comm)==MPI_COMM_NULL){
+ smpi_comm_init_smp(comm);
+ }
+ int num_core=1;
+ if (smpi_comm_is_uniform(comm)){
+ num_core = smpi_comm_size(smpi_comm_get_intra_comm(comm));
+ }
+ /*
+ #ifdef MPICH2_REDUCTION
+ MPI_User_function * uop = MPIR_Op_table[op % 16 - 1];
+ #else
+ MPI_User_function *uop;
+ struct MPIR_OP *op_ptr;
+ op_ptr = MPIR_ToPointer(op);
+ uop = op_ptr->op;
+ #endif
+ */
+ comm_size = smpi_comm_size(comm);
+ rank = smpi_comm_rank(comm);
+ MPI_Aint extent;
+ extent = smpi_datatype_get_extent(dtype);
+ tmp_buf = (void *) smpi_get_tmp_sendbuffer(count * extent);
+
+ /* compute intra and inter ranking */
+ int intra_rank, inter_rank;
+ intra_rank = rank % num_core;
+ inter_rank = rank / num_core;
+
+ /* size of processes participate in intra communications =>
+ should be equal to number of machines */
+ int inter_comm_size = (comm_size + num_core - 1) / num_core;
+
+ /* copy input buffer to output buffer */
+ smpi_mpi_sendrecv(send_buf, count, dtype, rank, tag,
+ recv_buf, count, dtype, rank, tag, comm, &status);
+
+ /* start binomial reduce intra communication inside each SMP node */
+ mask = 1;
+ while (mask < num_core) {
+ if ((mask & intra_rank) == 0) {
+ src = (inter_rank * num_core) + (intra_rank | mask);
+ if (src < comm_size) {
+ smpi_mpi_recv(tmp_buf, count, dtype, src, tag, comm, &status);
+ smpi_op_apply(op, tmp_buf, recv_buf, &count, &dtype);
+ }
+ } else {
+ dst = (inter_rank * num_core) + (intra_rank & (~mask));
+ smpi_mpi_send(recv_buf, count, dtype, dst, tag, comm);
+ break;
+ }
+ mask <<= 1;
+ } /* end binomial reduce intra-communication */
+
+
+ /* start rdb (recursive doubling) all-reduce inter-communication
+ between each SMP nodes : each node only have one process that can communicate
+ to other nodes */
+ if (intra_rank == 0) {
+
+ /* find nearest power-of-two less than or equal to inter_comm_size */
+ int pof2, rem, newrank, newdst;
+ pof2 = 1;
+ while (pof2 <= inter_comm_size)
+ pof2 <<= 1;
+ pof2 >>= 1;
+ rem = inter_comm_size - pof2;
+
+ /* In the non-power-of-two case, all even-numbered
+ processes of rank < 2*rem send their data to
+ (rank+1). These even-numbered processes no longer
+ participate in the algorithm until the very end.
+ */
+ if (inter_rank < 2 * rem) {
+ if (inter_rank % 2 == 0) {
+ dst = rank + num_core;
+ smpi_mpi_send(recv_buf, count, dtype, dst, tag, comm);
+ newrank = -1;
+ } else {
+ src = rank - num_core;
+ smpi_mpi_recv(tmp_buf, count, dtype, src, tag, comm, &status);
+ smpi_op_apply(op, tmp_buf, recv_buf, &count, &dtype);
+ newrank = inter_rank / 2;
+ }
+ } else {
+ newrank = inter_rank - rem;
+ }
+
+ /* example inter-communication RDB rank change algorithm
+ 0,4,8,12..36 <= true rank (assume 4 core per SMP)
+ 0123 4567 89 <= inter_rank
+ 1 3 4567 89 (1,3 got data from 0,2 : 0,2 will be idle until the end)
+ 0 1 4567 89
+ 0 1 2345 67 => newrank
+ */
+
+ if (newrank != -1) {
+ mask = 1;
+ while (mask < pof2) {
+ newdst = newrank ^ mask;
+ /* find real rank of dest */
+ dst = (newdst < rem) ? newdst * 2 + 1 : newdst + rem;
+ dst *= num_core;
+
+ /* exchange data in rdb manner */
+ smpi_mpi_sendrecv(recv_buf, count, dtype, dst, tag, tmp_buf, count, dtype,
+ dst, tag, comm, &status);
+ smpi_op_apply(op, tmp_buf, recv_buf, &count, &dtype);
+ mask <<= 1;
+ }
+ }
+
+ /* non pof2 case
+ left-over processes (all even ranks: < 2 * rem) get the result
+ */
+ if (inter_rank < 2 * rem) {
+ if (inter_rank % 2) {
+ smpi_mpi_send(recv_buf, count, dtype, rank - num_core, tag, comm);
+ } else {
+ smpi_mpi_recv(recv_buf, count, dtype, rank + num_core, tag, comm, &status);
+ }
+ }
+ }
+
+ /* start binomial broadcast intra-communication inside each SMP nodes */
+ int num_core_in_current_smp = num_core;
+ if (inter_rank == (inter_comm_size - 1)) {
+ num_core_in_current_smp = comm_size - (inter_rank * num_core);
+ }
+ mask = 1;
+ while (mask < num_core_in_current_smp) {
+ if (intra_rank & mask) {
+ src = (inter_rank * num_core) + (intra_rank - mask);
+ smpi_mpi_recv(recv_buf, count, dtype, src, tag, comm, &status);
+ break;
+ }
+ mask <<= 1;
+ }
+ mask >>= 1;
+
+ while (mask > 0) {
+ dst = (inter_rank * num_core) + (intra_rank + mask);
+ if (dst < comm_size) {
+ smpi_mpi_send(recv_buf, count, dtype, dst, tag, comm);
+ }
+ mask >>= 1;
+ }
+
+ smpi_free_tmp_buffer(tmp_buf);
+ return MPI_SUCCESS;
+}
