Changes between Version 4 and Version 5 of mpich/point_to_point/demo2

Timestamp:

Jun 12, 2008, 4:39:50 PM (16 years ago)

Author:

wade

Comment:

--

mpich/point_to_point/demo2

@@ -1 +1 @@
 {{{
 /* Program:
- *   每個 node 將自己的 id 送給下一個 node。
+ *   每個 node 將自己的 id 資訊送給下一個 node。
  * History:
  *   2008-06-05 BETA
+ *   2008-06-06 改變 #30 printf 位置，以了解 MPI 函式執行順序關係
+ *   2008-06-12 更改顯示方法。
  */
 
@@ -11 +13 @@
 int main(int argc,char *argv[])
 {
-  int n=0, myid, numprocs, i=0;
+  int n, myid, numprocs;
   MPI_Status status;
   MPI_Init(&argc,&argv);
   MPI_Comm_size(MPI_COMM_WORLD,&numprocs);
   MPI_Comm_rank(MPI_COMM_WORLD,&myid);
+
+  /* node 0 will send the first message */
   if(myid==0)
   {
+    n = myid;
     MPI_Send(&n, 1, MPI_INT, 1, 99, MPI_COMM_WORLD);
+    printf("[Ndde %d]「%d」 >> [Node %d]\n\n", myid, n, myid+1);
   }
-  if(myid!=0)
+
+  /* node 1 to node n-2 will send message to the next node */
+  if(myid>0 && myid<numprocs-1)
   {
     MPI_Recv(&n, 1, MPI_INT, myid-1, 99, MPI_COMM_WORLD, &status);
-    n++;
-
-    if(myid<numprocs-1)
-
-    {
-
-      MPI_Send(&n, 1, MPI_INT, myid+1, 99, MPI_COMM_WORLD);
-
-      printf("I am node %d\nI recive number %d from %d\n", myid, n, myid-1);
-      printf("I send number %d to %d\n\n", n, myid+1);
-
-    }
-
+    printf("[Node %d] << 「%d」[Node %d]\n", myid, n, status.MPI_SOURCE);
+    n = myid;
+    MPI_Send(&n, 1, MPI_INT, myid+1, 99, MPI_COMM_WORLD);
+    printf("[Ndde %d]「%d」 >> [Node %d]\n\n", myid, n, myid+1);
   }
 
+  /* the final node n-1 will not send any message but receive*/
+  if(myid==numprocs-1)
+  {
+    MPI_Recv(&n, 1, MPI_INT, myid-1, 99, MPI_COMM_WORLD, &status);
+    printf("[Node %d] << 「%d」[Node %d]\n", myid, n, status.MPI_SOURCE);
+  }
   MPI_Finalize();
-
  return 0;
-
-}
 }}}