+
+
+#ifdef DEBUG_REDUCE
+/**
+ * debugging helper function
+ **/
+void print_buffer_int( void *buf, int len, char *msg, int rank) ;
+void print_buffer_int( void *buf, int len, char *msg, int rank) {
+ int tmp, *v;
+ printf("**[%d] %s: ",rank,msg);
+ for (tmp=0;tmp<len;tmp++) {
+ v = buf;
+ printf("[%d]", v[tmp] );
+ }
+ printf("\n");
+ free(msg);
+}
+#endif
+
+/**
+ * MPI_Reduce
+ **/
+int SMPI_MPI_Reduce( void *sendbuf, void *recvbuf, int count, MPI_Datatype datatype,
+ MPI_Op op, int root, MPI_Comm comm )
+{
+ int retval = MPI_SUCCESS;
+ int rank;
+ int size;
+ int i;
+ int tag=0;
+ smpi_mpi_request_t *tabrequest;
+ smpi_mpi_request_t request;
+
+ smpi_bench_end();
+
+ rank = smpi_mpi_comm_rank(comm);
+ size = comm->size;
+
+ if (rank != root) { // if i am not ROOT, simply send my buffer to root
+
+#ifdef DEBUG_REDUCE
+ print_buffer_int( sendbuf, count, xbt_strdup("sndbuf"),rank);
+#endif
+ retval = smpi_create_request(sendbuf, count, datatype, rank, root, tag , comm, &request);
+ smpi_mpi_isend(request);
+ smpi_mpi_wait(request, MPI_STATUS_IGNORE);
+ xbt_mallocator_release(smpi_global->request_mallocator, request);
+
+ } else {
+ // i am the ROOT: wait for all buffers by creating one request by sender
+ tabrequest = xbt_malloc((size-1)*sizeof(smpi_mpi_request_t));
+
+ void **tmpbufs = xbt_malloc((size-1)*sizeof(void *));
+ for (i=0; i<size-1; i++) {
+ // we need 1 buffer per request to store intermediate receptions
+ tmpbufs[i] = xbt_malloc(count*datatype->size);
+ }
+ memcpy(recvbuf,sendbuf,count*datatype->size*sizeof(char)); // initiliaze recv buf with my own snd buf
+
+ // i can not use: 'request->forward = size-1;' (which would progagate size-1 receive reqs)
+ // since we should op values as soon as one receiving request matches.
+ for (i=0; i<comm->size-1; i++) {
+ // reminder: for smpi_create_request() the src is always the process sending.
+ retval = smpi_create_request(tmpbufs[i], count, datatype,
+ MPI_ANY_SOURCE, root,
+ tag, comm, &(tabrequest[i]));
+ if (NULL != tabrequest[i] && MPI_SUCCESS == retval) {
+ if (MPI_SUCCESS == retval) {
+ smpi_mpi_irecv(tabrequest[i]);
+ }
+ }
+ }
+ // now, wait for completion of all irecv's.
+ for (i=0; i<comm->size-1; i++) {
+ int index = MPI_UNDEFINED;
+ smpi_mpi_waitany(comm->size-1, tabrequest, &index, MPI_STATUS_IGNORE);
+
+#ifdef DEBUG_REDUCE
+ printf("MPI_Waitany() unblocked: root received (completes req[index=%d])\n",index);
+ print_buffer_int( tmpbufs[index], count, bprintf("tmpbufs[index=%d]",index),rank);
+#endif
+
+ // arg 2 is modified
+ op->func (tmpbufs[index],recvbuf,&count,&datatype);
+#ifdef DEBUG_REDUCE
+ print_buffer_int( recvbuf, count, xbt_strdup("rcvbuf"),rank);
+
+#endif
+ //xbt_mallocator_release(smpi_global->request_mallocator, tabrequest[i]);
+ xbt_free( tmpbufs[index]);
+ }
+ xbt_free(tabrequest);
+ xbt_free(tmpbufs);
+ }
+
+ smpi_bench_begin();
+
+ return retval;
+}
+