If there is just one node, we don't need a decision function, just do the copy

and return.

This commit was SVN r12199.

ompi/mca/coll/tuned/coll_tuned_decision_fixed.c

@@ -214,6 +214,14 @@ int ompi_coll_tuned_reduce_intra_dec_fixed( void *sendbuf, void *recvbuf,
         return (err);
     }
 
+    /* handle special case when size == 1 */
+    if( 1 == comsize ) {
+        if( sendbuf != MPI_IN_PLACE ) {
+            ompi_ddt_copy_content_same_ddt( datatype, count, (char*)recvbuf, (char*)sendbuf );
+        }
+        return MPI_SUCCESS;
+    }
+
     msgsize = dsize * count;   /* needed for decision */
 
     /* for small messages use linear algorithm */