updated hw6 src

git-svn-id: svn://anubis/gvsu@240 45c1a28c-8058-47b2-ae61-ca45b979098e

cs677/hw6/src/mpi-round-trip.cc

@@ -1,50 +1,109 @@
 
 #include <iostream>
 #include <sys/time.h>
+#include <unistd.h>     /* gethostname() */
+#include <stdlib.h>     /* rand() */
 #include <mpi.h>
 using namespace std;
 
+#define TRIALS 100
+
+double sendAndTime(int length);
+void receive(int length);
+
 int main(int argc, char * argv[])
 {
     int my_rank;
+    double max_bytes_per_sec = 0.0;
+    int max_bps_pkt_size = 0;
+    char hostname[256];
 
     MPI_Init(&argc, &argv);
     MPI_Comm_rank(MPI_COMM_WORLD, &my_rank);
 
     if (my_rank == 0)
     {
-        int buf = 0;
-        struct timeval before, after;
-
-        gettimeofday(&before, NULL);        /* Start timing */
-
-        MPI_Send(&buf, sizeof(buf), MPI_CHAR,
-            0, 42, MPI_COMM_WORLD);
-
-        MPI_Recv(&buf, sizeof(buf), MPI_CHAR,
-            MPI_ANY_SOURCE, MPI_ANY_TAG, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
-
-        gettimeofday(&after, NULL);         /* Stop timing */
-
-        cout << "Master received " << buf << endl;
-
-        double time_before = before.tv_sec + before.tv_usec / 1000000.0;
-        double time_after = after.tv_sec + after.tv_usec / 1000000.0;
-        double diff = time_after - time_before;
-        cout << "Elapsed time: " << diff << " seconds." << endl;
+        MPI_Recv(&hostname[0], 256, MPI_CHAR, MPI_ANY_SOURCE,
+            MPI_ANY_TAG, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
+        cout << "Remote host name: " << hostname << endl;
     }
     else
     {
-        int forty_two = 42;
-        int buf;
-        MPI_Recv(&buf, sizeof(buf), MPI_CHAR,
-            MPI_ANY_SOURCE, MPI_ANY_TAG, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
+        gethostname(&hostname[0], 255);
+        MPI_Send(&hostname[0], 256, MPI_CHAR, 0, 42, MPI_COMM_WORLD);
+    }
 
-        MPI_Send(&forty_two, sizeof(forty_two), MPI_CHAR,
-            0, 42, MPI_COMM_WORLD);
+    for (int length = 100; length < 100000; length += 100)
+    {
+        if (my_rank == 0)
+        {
+            cout << "Testing packet length " << length << endl;
+            double rtt = sendAndTime(length);
+            double bytes_per_sec = (length * TRIALS) / rtt;
+            if (bytes_per_sec > max_bytes_per_sec)
+            {
+                max_bps_pkt_size = length;
+                max_bytes_per_sec = bytes_per_sec;
+            }
+        }
+        else
+        {
+            receive(length);
+        }
+    }
+
+    if (my_rank == 0)
+    {
+        cout << "Maximum bytes per second (round trip) was " << max_bytes_per_sec << endl;
+        cout << "This occurred with a packet size of " << max_bps_pkt_size << endl;
+    }
+    else
+    {
+        cout << "Slave exiting." << endl;
     }
 
     MPI_Finalize();
 
     return 0;
 }
+
+double sendAndTime(int length)
+{
+    char buff[length];
+    for (int i = 0; i < length; i++)
+    {
+        buff[i] = rand() & 0xFF;
+    }
+
+    struct timeval before, after;
+    gettimeofday(&before, NULL);        /* Start timing */
+
+    for (int i = 0; i < TRIALS; i++)
+    {
+        int ret = MPI_Send(&buff, length, MPI_CHAR, 0, 42, MPI_COMM_WORLD);
+//        cout << "MPI_Send() returned " << ret << endl;
+
+        MPI_Recv(&buff, length, MPI_CHAR,
+            MPI_ANY_SOURCE, MPI_ANY_TAG, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
+    }
+
+    gettimeofday(&after, NULL);         /* Stop timing */
+
+    double time_before = before.tv_sec + before.tv_usec / 1000000.0;
+    double time_after = after.tv_sec + after.tv_usec / 1000000.0;
+    double diff = time_after - time_before;
+    return diff;
+}
+
+void receive(int length)
+{
+    char buff[length];
+
+    for (int i = 0; i < TRIALS; i++)
+    {
+        MPI_Recv(&buff, length, MPI_CHAR,
+            MPI_ANY_SOURCE, MPI_ANY_TAG, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
+
+        MPI_Send(&buff, length, MPI_CHAR, 0, 42, MPI_COMM_WORLD);
+    }
+}