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hotplate.c
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hotplate.c
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/* A program to solve the hotplate problem in a parallel fashion having a near
* linear speed up as thread increase
Author: Bukola Grace Omotoso
MNumber: M01424979
ID: bgo2e
Last Code Clean-up: 10/22/2018, 2:20am
*/
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <math.h>
#include <string.h>
#include <unistd.h>
#include <pthread.h>
#include <sys/time.h>
#include <stdio.h>
#include "mpi.h"
/* Build memory structure for hotplate*/
float** buildHotplate(int rows, int columns) {
float** hotplate;
hotplate = (float**) malloc(rows*sizeof(float*));
for (int i = 0; i < rows; i++)
hotplate[i] = (float*) malloc(columns*sizeof(float));
return hotplate;
}
void initializeHotPlate(int num_rows, int num_cols, float** hotplate, float** hotplateClone, int top_temp, int left_temp, int right_temp, int bottom_temp) {
int num_outer_grid = (2 * num_rows) + (2 * (num_cols - 2));
float outer_grid_sum = (top_temp * (num_cols - 2)) + (left_temp * (num_rows - 1)) + (bottom_temp * num_cols) + (right_temp * (num_rows - 1));
float initial_inner_val = outer_grid_sum / num_outer_grid;
for (int row = 0; row < num_rows; row++) {
for (int column = 0; column < num_cols; column++) {
//top values override the top row except the edges
if ((row == 0) & (column != 0 & column != num_cols - 1)) {
hotplate[row][column] = top_temp;
hotplateClone[row][column] = top_temp;
}
else if (column == 0 && (row != (num_rows-1))) {
hotplate[row][column] = left_temp;
hotplateClone[row][column] = left_temp;
}
else if (column == (num_cols - 1) && (row != (num_rows-1))) {
hotplate[row][column] = right_temp;
hotplateClone[row][column] = right_temp;
}
else if(row == (num_rows -1 )){
hotplate[row][column] = bottom_temp;
hotplateClone[row][column] = bottom_temp;
}
if ((row != 0) && (row != num_rows - 1) && (column != 0) && (column != num_cols - 1))
hotplate[row][column] = initial_inner_val;
}
}
}
/*Get the maximum values from all threads*/
float max_max_diff(float arr[], int n)
{
int i;
float max = arr[0];
for (i = 1; i < n; i++)
if (arr[i] > max)
max = arr[i];
return max;
}
/* Swap hotplate and its clone*/
void swapHotplate(float *a, float *b) {
float tmp = *a;
*a = *b;
*b = tmp;
}
void swapHotplate2(float **hotplate, float **hotplateClone, int num_rows, int num_cols, int offset, int stop, int proc_id) {
if (offset == 1)
offset--;
if (stop >= num_rows)
stop = num_rows - 1;
float *tmp;
for(int row = offset; row < stop; row++){
for(int col = 0; col < num_cols; col++){
float tmp = hotplate[row][col];
hotplate[row][col] = hotplateClone[row][col];
hotplateClone[row][col] = tmp;
}
}
}
/* Get current time*/
double timestamp()
{
struct timeval tval;
gettimeofday( &tval, ( struct timezone * ) 0 );
return ( tval.tv_sec + (tval.tv_usec / 1000000.0) );
}
float generateHeat2(float** hotplate, float** hotplateClone, int offset, int chunksize, int proc_id, int num_rows, int num_cols){
int start_row = (proc_id - 1)*chunksize;
int stop_row = proc_id*chunksize;
if (proc_id == 1)
start_row = 1;
if (stop_row >= num_rows)
stop_row = num_rows-1;
float max_difference = 0;
float previous_val;
float current_val;
float diff, max_epsilon_val;
for (int row = start_row; row < stop_row; row++) {
for (int column = 1; column < (num_cols - 1); column++) {
previous_val = hotplate[row][column];
current_val = ((hotplate[row - 1][column] + hotplate[row][column - 1] + hotplate[row + 1][column] + hotplate[row][column + 1]) / 4);
diff = fabsf(previous_val - current_val);
if (diff > max_difference){
max_difference = diff;
}
hotplateClone[row][column] = current_val;
}
}
swapHotplate2(hotplate, hotplateClone, num_rows, num_cols, start_row, stop_row, proc_id);
return max_difference;
}
int main(int argc, char *argv[])
{
float max_epsilon_val;
long int sum, partial_sum;
int num_rows = atoi(argv[1]);
int num_cols = atoi(argv[2]);
int top_temp = atoi(argv[3]);
int left_temp = atoi(argv[4]);
int right_temp = atoi(argv[5]);
int bottom_temp = atoi(argv[6]);
float epsilon = atof(argv[7]);
float** hotplate;
float** hotplateClone;
hotplate = buildHotplate(num_rows, num_cols);
hotplateClone = buildHotplate(num_rows, num_cols);
initializeHotPlate(num_rows, num_cols, hotplate, hotplateClone, top_temp, left_temp, right_temp, bottom_temp);
float max_difference = 0;
float global_max = epsilon + 1;
float previous_val;
float current_val;
float diff, max_epsilon_val_received;
double begin, end;
MPI_Status status;
int rc, proc_id, mgr_process = 0, i, num_procs,
cur_id, start_row_to_receive, row_per_proc,
sender, start_row_received, start_row, stop_row, start_row_to_send, offset, chunksize, tag1, tag2, tag3, tag4;
float cur_max_epsilon = epsilon + 1;
float cur_max_difference = 0.0;
int counter = 0;
MPI_Init(&argc, &argv);
rc = MPI_Comm_rank(MPI_COMM_WORLD, &proc_id);
rc = MPI_Comm_size(MPI_COMM_WORLD, &num_procs);
int working_proc = num_procs - 1;
chunksize = (num_rows + working_proc - 1)/working_proc;
tag2 = 1;
tag1 = 2;
tag3 = 4;
tag4 = 3;
int break_from_loop = 0;
begin = timestamp();
while(break_from_loop != 1){
if(proc_id == mgr_process){
alarm(180);
/* Send each task its portion of the array - master keeps 1st part */
offset = 0;
for (int dest=1; dest<=working_proc; dest++) {
MPI_Send(&offset, 1, MPI_INT, dest, tag1, MPI_COMM_WORLD);
MPI_Send(&hotplate[offset][0], chunksize, MPI_FLOAT, dest, tag2, MPI_COMM_WORLD);
MPI_Send(&hotplateClone[offset][0], chunksize, MPI_FLOAT, dest, tag3, MPI_COMM_WORLD);
offset = offset + chunksize;
}
for (i=1; i<=working_proc; i++) {
int source = i;
MPI_Recv(&offset, 1, MPI_INT, source, tag1, MPI_COMM_WORLD, &status);
MPI_Recv(&hotplate[offset][0], chunksize, MPI_FLOAT, source, tag2, MPI_COMM_WORLD, &status);
MPI_Recv(&hotplateClone[offset][0], chunksize, MPI_FLOAT, source, tag3, MPI_COMM_WORLD, &status);
}
/* Get final sum and print sample results */
MPI_Reduce(&max_difference, &global_max, 1, MPI_FLOAT, MPI_MAX, mgr_process, MPI_COMM_WORLD);
if ((counter > 0 && (counter & (counter - 1)) == 0 )|| global_max < epsilon)
printf("%-10d%10.6f\n", counter, global_max);
if (global_max < epsilon){
break_from_loop = 1;
end = timestamp();
printf("%s%5.2f\n","TOTAL TIME: ", (end-begin));
}
counter++;
}
if (proc_id > mgr_process) {
alarm(180);
/* Receive my portion of array from the master task */
int source = mgr_process;
MPI_Recv(&offset, 1, MPI_INT, source, tag1, MPI_COMM_WORLD, &status);
MPI_Recv(&hotplate[offset][0], chunksize, MPI_FLOAT, source, tag2,
MPI_COMM_WORLD, &status);
MPI_Recv(&hotplateClone[offset][0], chunksize, MPI_FLOAT, source, tag3,
MPI_COMM_WORLD, &status);
max_difference = generateHeat2(hotplate, hotplateClone, offset, chunksize, proc_id, num_rows, num_cols);
MPI_Send(&offset, 1, MPI_INT, mgr_process, tag1, MPI_COMM_WORLD);
MPI_Send(&hotplate[offset][0], chunksize, MPI_FLOAT, mgr_process, tag2, MPI_COMM_WORLD);
MPI_Send(&hotplateClone[offset][0], chunksize, MPI_FLOAT, mgr_process, tag3, MPI_COMM_WORLD);
MPI_Reduce(&max_difference, &global_max, 1, MPI_FLOAT, MPI_MAX, mgr_process, MPI_COMM_WORLD);
}
MPI_Bcast(&break_from_loop, 1, MPI_INT, mgr_process, MPI_COMM_WORLD);
}
MPI_Finalize();
return 0;
}