stuff

L17/mpi_world.c

+#include <stdio.h>
+#include <stdlib.h>
+#include <mpi.h>
+
+int main(int argc, char** argv) {
+
+    MPI_Init (&argc, &argv);
+
+    int rank, size;
+    MPI_Comm_rank(MPI_COMM_WORLD,&rank);
+    MPI_Comm_size(MPI_COMM_WORLD,&size);
+    char name[MPI_MAX_PROCESS_NAME];
+    int name_len;
+    MPI_Get_processor_name(name,&name_len);
+    printf ("name = %s\n",name);
+    
+    printf ("Hello World! from MPI rank %d, number of ranks = %d\n",rank,size);
+
+    MPI_Finalize();
+}

L17/omp_extreme.c

+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include <omp.h>
+#include "vec.h"
+
+int main (int argc, char* argv[]) {
+
+    // get num_threads from the command line
+    if (argc < 2) {
+        printf ("Command usage : %s %s\n",argv[0],"num_threads");
+        return 1;
+    }
+    int num_threads = atoi(argv[1]);
+    omp_set_num_threads(num_threads);
+
+    // read the number of points and the dimension of each point
+    int num_points, dim;
+    if (scanf("%*c %d %d",&num_points, &dim) != 2) {
+        printf ("error reading the number of points and the dimension\n");
+        return 1;
+    }
+
+    // read vectors from stdin and store them in a 2d array
+    double* data = (double*)malloc(num_points*dim*sizeof(double));
+    if (data == NULL) {
+        printf ("malloc return NULL pointer!\n");
+        return 1;
+    }
+    for (int i=0;i<num_points;i++) {
+        if (vec_read_stdin(data+i*dim,dim) != dim) {
+            printf ("error reading the next point from stdin\n");
+            return 1;
+        }
+    }
+
+    // start the timer
+    double start_time, end_time;
+    start_time = omp_get_wtime();
+
+    // find the extreme pair
+    double max_dist_sq = 0;
+    int extreme[2];
+    int pairs_checked = 0;
+
+#pragma omp parallel default(none) shared(dim,data,pairs_checked,max_dist_sq,extreme,num_points,num_threads)
+    {
+        double thread_max_dist_sq = 0;
+        int thread_extreme[2];
+        int thread_pairs_checked = 0;
+        int thread_num = omp_get_thread_num();
+#ifdef DYNAMIC
+#pragma omp for schedule(dynamic)
+#else 
+#pragma omp for schedule(static)
+#endif
+        for (int i=0;i<num_points-1;i++) {
+            for (int j=i+1;j<num_points;j++) {
+                double dist_sq = vec_dist_sq(data+i*dim,data+j*dim,dim);
+                thread_pairs_checked += 1;
+                if (dist_sq > thread_max_dist_sq) {
+                    thread_max_dist_sq = dist_sq;
+                    thread_extreme[0] = i;
+                    thread_extreme[1] = j;
+                }
+            }
+        }
+#ifdef DEBUG
+        printf ("thread %d checked %d pairs\n",thread_num,thread_pairs_checked);
+#endif
+#pragma omp critical
+        {
+            pairs_checked += thread_pairs_checked;
+            if (thread_max_dist_sq > max_dist_sq) {
+                max_dist_sq = thread_max_dist_sq;
+                extreme[0] = thread_extreme[0];
+                extreme[1] = thread_extreme[1];
+            }
+        }
+
+    }
+
+    // stop the timer
+    end_time = omp_get_wtime();
+
+    // output the results
+#ifdef TIMING
+    printf ("(%d,%.4f),",num_threads,end_time-start_time);
+#else    
+    printf ("num_threads = %d, ",num_threads);
+    printf ("elapsed time = %.6f seconds\n",end_time-start_time);
+    printf ("pairs checked = %d\n",pairs_checked);        
+    printf ("Extreme Distance = %.2f\n",sqrt(max_dist_sq));
+    printf ("Extreme Pair = %d %d\n",extreme[0],extreme[1]);
+#endif    
+
+    // free memory allocated for dataset 
+    free(data);
+}

L17/omp_extreme.sh

+# make sure we are running on matrix!
+if [ "$HOSTNAME" != matrix ]; then
+    printf "error : can only run this script on matrix!\n"
+    exit 1
+fi
+
+# check to make sure we provided a command line argument for the filename
+if [ "$#" -ne 1 ]
+then
+  echo "error: please specify filename as a command line argument"
+  exit 1
+fi
+
+# compile using TIMING flag
+gcc -DTIMING -DDYNAMIC -O3 -o omp_extreme omp_extreme.c vec.c -lm -fopenmp
+
+# run multiple times for scaling study
+cat $1 | ./omp_extreme 1
+cat $1 | ./omp_extreme 2
+cat $1 | ./omp_extreme 4
+cat $1 | ./omp_extreme 8
+
+# print new line
+printf '\n'

L17/omp_extreme_arc.dynamic

+(1,1.5658),(2,0.7934),(4,0.3999),(8,0.2092),(16,0.1122),(32,0.0625)
\ No newline at end of file

L17/omp_extreme_arc.static

+(1,1.5626),(2,1.1806),(4,0.6941),(8,0.3816),(16,0.2039),(32,0.1162)
\ No newline at end of file

L17/omp_extreme_sb.sh

+#!/bin/bash
+#SBATCH -A cmda3634_rjh
+#SBATCH -p normal_q
+#SBATCH -t 10
+#SBATCH --cpus-per-task=32
+#SBATCH -o omp_extreme.out
+
+# check to make sure we provided a command line argument for the filename
+if [ "$#" -ne 1 ]
+then
+  echo "error: please specify filename as a command line argument"
+  exit 1
+fi
+
+# Go to the directory where the job was submitted
+cd $SLURM_SUBMIT_DIR
+
+# Load the modules (including the gcc compiler!)
+module load matplotlib
+
+# compile using TIMING flag
+gcc -DTIMING -DDYNAMIC -O3 -o omp_extreme omp_extreme.c vec.c -lm -fopenmp
+
+# OpenMP settings
+export OMP_NUM_THREADS=$SLURM_CPUS_PER_TASK
+export OMP_PROC_BIND=true
+
+# run multiple times for scaling study
+cat $1 | ./omp_extreme 1
+cat $1 | ./omp_extreme 2
+cat $1 | ./omp_extreme 4
+cat $1 | ./omp_extreme 8
+cat $1 | ./omp_extreme 16
+cat $1 | ./omp_extreme 32

L17/vec.c

+#include <stdio.h>
+
+// v = 0
+void vec_zero (double v[], int dim) {
+    for (int i=0;i<dim;i++) {
+        v[i] = 0;
+    }
+}
+
+// read a vector from stdin
+// returns the number of elements read in
+int vec_read_stdin (double v[], int dim) {
+    for (int i=0;i<dim;i++) {
+        if (scanf("%lf",&(v[i])) != 1) { // could also use v+i
+            return i;
+        }
+    }
+    return dim;
+}
+
+// w = u + v
+void vec_add (double u[], double v[], double w[], int dim) {
+    for (int i=0;i<dim;i++) {
+        w[i] = u[i] + v[i];
+    }
+}
+
+// w = cv
+void vec_scalar_mult (double v[], double c, double w[], int dim) {
+    for (int i=0;i<dim;i++) {
+        w[i] = c*v[i];
+    }
+}
+
+// print a vector using the given format specifier
+void vec_print (double v[], char* format, int dim) {
+    for (int i=0;i<dim;i++) {
+        printf (format,v[i]);
+    }
+    printf ("\n");
+}
+
+// calculate the norm squared of a vector
+double vec_norm_sq (double v[], int dim) {
+    double norm_sq = 0;
+    for (int i=0;i<dim;i++) {
+        norm_sq += v[i]*v[i];
+    }
+    return norm_sq;
+}
+
+// calculate the distance squared between two vectors
+double vec_dist_sq (double u[], double v[], int dim) {
+    double dist_sq = 0;
+    for (int i=0;i<dim;i++) {
+        dist_sq += (u[i]-v[i])*(u[i]-v[i]);
+    }
+    return dist_sq;
+}
+
+// performs the copy v->data[i] = w->data[i] for all i
+void vec_copy (double v[], double w[], int dim) {
+    for (int i=0;i<dim;i++) {
+        v[i] = w[i];
+    }
+}

L17/vec.h

+#ifndef VEC_H
+#define VEC_H
+
+// v = 0
+void vec_zero (double v[], int dim);
+
+// read a vector from stdin
+// returns the number of elements read in
+int vec_read_stdin (double v[], int dim);
+
+// w = u + v
+void vec_add (double u[], double v[], double w[], int dim);
+
+// w = cv
+void vec_scalar_mult (double v[], double c, double w[], int dim);
+
+// print a vector using the given format specifier
+void vec_print (double v[], char* format, int dim);
+
+// calculate the norm squared of a vector
+double vec_norm_sq (double v[], int dim);
+
+// calculate the distance squared between two vectors
+double vec_dist_sq (double u[], double v[], int dim);
+
+// performs the copy v->data[i] = w->data[i] for all i
+void vec_copy (double v[], double w[], int dim);
+
+#endif