Changes between Version 1 and Version 2 of mpich/point_to_point/demo2

Timestamp:

Jun 10, 2008, 4:27:31 PM (16 years ago)

Author:

wade

Comment:

--

mpich/point_to_point/demo2

@@ +1 @@
+{{{
 /* Program:
  *   每個 node 將自己的 id 送給下一個 node。
@@ -42 +43 @@
 
 }
+}}}
+----
+有問題，為什麼 node 0 沒有 send 任何 message ，而其它的 node 卻能執行。怒…。
+{{{
+#include <mpi.h>
+#include <stdio.h>
 
+int main(int argc,char *argv[])
+{
+  int n, myid, numprocs, i=0;
+  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 = 0;
+    /*
+    MPI_Send(&n, 1, MPI_INT, 1, 99, MPI_COMM_WORLD);
+    */
+    printf("[Ndde %d] send number %d to Node %d\n\n", myid, n, myid+1);
+  }
+
+  /* node 1 to node n-2 will send message to the next node */
+  if(myid<numprocs-1)
+  {
+    MPI_Recv(&n, 1, MPI_INT, myid-1, 99, MPI_COMM_WORLD, &status);
+    printf("[Node %d] recive number %d\n", myid, n);
+    n = myid;
+    MPI_Send(&n, 1, MPI_INT, myid+1, 99, MPI_COMM_WORLD);
+    printf("[Ndde %d] send number %d to Node %d\n\n", myid, n, myid+1);
+  }
+
+  /* the final node n-1 will will not send any message but print itself*/
+  if(myid==numprocs-1)
+  {
+    MPI_Recv(&n, 1, MPI_INT, myid-1, 99, MPI_COMM_WORLD, &status);
+    printf("[Node %d] recive number %d\n", myid, n);
+  }
+  MPI_Finalize();
+ return 0;
+}
+
+{{{
+
+}}}