ModSim ass4 taddeus: Finished part 1 and made a least squares data fitting script.

modsim/ass4_taddeus/ring.c

-#include <stdlib.h>
-#include <stdio.h>
-#include <mpi.h>
-
-double data[1] = {.0};
-
-void initialize_ring(int tasks) {
-    double received;
-    MPI_Status status;
-
-    printf("Sending first data...");
-    MPI_Send(data, 1, MPI_DOUBLE, 1, 0, MPI_COMM_WORLD);
-    puts("sent");
-    MPI_Recv(&received, 1, MPI_DOUBLE, tasks - 1, MPI_ANY_TAG, MPI_COMM_WORLD,
-            &status);
-
-    if( received != *data )
-        printf("Received data does not match (sent: %f, received: %f)\n",
-                *data, received);
-    else
-        puts("Data received succesfully");
-}
-
-void pass_data(int tasks, int rank) {
-    double received;
-    MPI_Status status;
-    int target = (rank + 1) % tasks, source = (rank - 1 + tasks) % tasks;
-
-    MPI_Recv(&received, 1, MPI_DOUBLE, source, MPI_ANY_TAG, MPI_COMM_WORLD,
-            &status);
-    printf("Task %d received data from %d, sending to %d...", rank, source,
-            target);
-    MPI_Send(data, 1, MPI_DOUBLE, target, 0, MPI_COMM_WORLD);
-    puts("sent");
-}
-
-int main(int argc, char **argv) {
-    int tasks, rank, error;
-
-    if( (error = MPI_Init(&argc, &argv)) != MPI_SUCCESS ) {
-        printf("MPI_init failed (error %d)\n", error);
-        MPI_Abort(MPI_COMM_WORLD, error);
-    }
-
-    MPI_Comm_size(MPI_COMM_WORLD, &tasks);
-    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
-
-    if( !rank )
-        initialize_ring(tasks);
-    else
-        pass_data(tasks, rank);
-
-    MPI_Finalize();
-}

modsim/ass4_taddeus/ring/plot.py

+#!/usr/bin/env python
+from sys import argv, stdin
+from pylab import array, matrix, ones, dot, plot, legend, show, savefig
+
+# Collect data
+data = []
+for line in stdin.readlines():
+    data.append(map(float, line.split(',', 1)))
+
+# Least squares data fit
+A = matrix(ones((len(data), 2)))
+data = array(data)
+A.T[1] = data.T[0]
+b = data.T[1].T
+start, slope = tuple(list(dot((A.T * A).I * A.T, b).tolist()[0]))
+
+# Plot and optionally save data
+data = data.T
+plot(data[0], data[1], 'x-', label='original data')
+plot([0, data[0][-1]], [start, data[0][-1] * slope + start], '-',
+     label='linear fit y = %ex + %e' % (slope, start))
+if len(argv) == 2:
+    savefig(argv[1])
+legend()
+show()

modsim/ass4_taddeus/ring/ring.c

+#include <stdlib.h>
+#include <stdio.h>
+#include <mpi.h>
+
+//#define DEBUG
+
+#define LOOP 100
+#define STRIDE 10000
+#define REPEAT 7
+
+const int data_size = LOOP * STRIDE;
+
+/*
+ * The master task measures the time between the sending and receiving of data.
+ */
+void master(int tasks) {
+    double *received = malloc(data_size * sizeof(double)),
+           *sent = malloc(data_size * sizeof(double)),
+           avg_time, start_time, time;
+    MPI_Status status;
+    int i, size, measurement, failures;
+
+    // generate data to send
+    for( i = 0; i < data_size; i++ )
+        sent[i] = .0;
+
+    // Increase the message length with a fixed STRIDE
+    for( size = STRIDE; size <= data_size; size += STRIDE ) {
+        // Repeat the measurement and average the results
+        avg_time = .0;
+
+        for( measurement = 1; measurement <= REPEAT; measurement++ ) {
+            #ifdef DEBUG
+            printf("Measurement %d: ", measurement);
+            #endif
+            start_time = MPI_Wtime();
+
+            //printf("0");
+            MPI_Send(sent, size, MPI_DOUBLE, 1, 0, MPI_COMM_WORLD);
+            //printf("...");
+            MPI_Recv(received, size, MPI_DOUBLE, tasks - 1, MPI_ANY_TAG,
+                    MPI_COMM_WORLD, &status);
+
+            time = MPI_Wtime() - start_time;
+
+            for( i = failures = 0; i < size; i++ )
+                if( received[i] != sent[i] )
+                    failures++;
+
+            //printf("0, %fs (%d failures)\n", time, failures);
+            #ifdef DEBUG
+            printf("%fs (%d failures)\n", time, failures);
+            #endif
+            avg_time += time;
+        }
+
+        avg_time /= REPEAT;
+
+        #ifdef DEBUG
+        printf("Average time for size %d: %fs\n", size, avg_time);
+        #else
+        printf("%d,%f\n", size, avg_time);
+        #endif
+    }
+
+    free(received);
+    free(sent);
+}
+
+/*
+ * A slave task passes the data to the next task in the ring.
+ */
+void slave(int tasks, int rank) {
+    double *data = malloc(data_size * sizeof(double));
+    MPI_Status status;
+    int size, measurement,
+        source = (rank - 1 + tasks) % tasks, target = (rank + 1) % tasks;
+
+    // Increase the message length with a fixed STRIDE
+    for( size = STRIDE; size <= data_size; size += STRIDE ) {
+        // Repeat the measurement
+        for( measurement = 1; measurement <= REPEAT; measurement++ ) {
+            MPI_Recv(data, size, MPI_DOUBLE, source, MPI_ANY_TAG,
+                    MPI_COMM_WORLD, &status);
+            //printf("%d", rank);
+            MPI_Send(data, size, MPI_DOUBLE, target, 0, MPI_COMM_WORLD);
+            //printf("...");
+        }
+    }
+
+    free(data);
+}
+
+int main(int argc, char **argv) {
+    int tasks, rank, error;
+
+    if( (error = MPI_Init(&argc, &argv)) != MPI_SUCCESS ) {
+        printf("MPI_init failed (error %d)\n", error);
+        MPI_Abort(MPI_COMM_WORLD, error);
+        return EXIT_FAILURE;
+    }
+
+    MPI_Comm_size(MPI_COMM_WORLD, &tasks);
+    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+
+    if( !rank )
+        master(tasks);
+    else
+        slave(tasks, rank);
+
+    MPI_Finalize();
+
+    return EXIT_SUCCESS;
+}

modsim/ass4_taddeus/ring_test.c → modsim/ass4_taddeus/ring/ring_test.c

@@ -40,6 +40,7 @@ int main(int argc, char **argv) {
     if( (error = MPI_Init(&argc, &argv)) != MPI_SUCCESS ) {
         printf("MPI_init failed (error %d)\n", error);
         MPI_Abort(MPI_COMM_WORLD, error);
+        return EXIT_FAILURE;
     }
 
     MPI_Comm_size(MPI_COMM_WORLD, &tasks);
@@ -51,4 +52,6 @@ int main(int argc, char **argv) {
         pass_data(tasks, rank);
 
     MPI_Finalize();
+
+    return EXIT_SUCCESS;
 }