222 lines
5.1 KiB
C
222 lines
5.1 KiB
C
#include <stdlib.h>
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#include <stdio.h>
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#include <mpi.h>
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#include <execinfo.h>
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#include <signal.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <errno.h>
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#define ARRAY_SIZE 1000000
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#define DEBUG 0
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void segfault_handler(int sig) {
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void *array[10];
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size_t size;
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size = backtrace(array, 10);
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fprintf(stderr, "[-] Error: signal %d:\n", sig);
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backtrace_symbols_fd(array, size, STDERR_FILENO);
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exit(1);
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}
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double* setup_send_array(int size) {
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double *arr = (double *)malloc(size * sizeof(double));
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if(arr == NULL) {
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printf("[-] Error: malloc failed!\n");
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exit(1);
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}
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for (int i = 0; i < size; i++) {
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arr[i] = (double)rand() / (double)RAND_MAX;
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}
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return arr;
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}
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double* setup_recv_array(int n_elements) {
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double *recv_arr = (double *)malloc(n_elements * sizeof(double));
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if(recv_arr == NULL) {
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printf("[-] Error: malloc failed!\n");
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exit(1);
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}
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for (int i = 0; i < n_elements; i++) {
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recv_arr[i] = 0.0;
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}
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return recv_arr;
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}
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void setup_displacements_and_counts(int *displacements, int *counts, int ntasks) {
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for(int i = 0; i < ntasks; i++) {
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displacements[i] = (int) (ARRAY_SIZE / ntasks * i); // my_start
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counts[i] = (int) (ARRAY_SIZE / ntasks * (i + 1)) - displacements[i]; // my_end - my_start
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}
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}
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int compare_doubles(const void *a, const void *b) {
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const double *da = (const double *) a;
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const double *db = (const double *) b;
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return (*da > *db) - (*da < *db);
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}
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double *finalize_sort(double* arr, int arr_size, int *displacements, int n_tasks) {
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double *temp_arr = (double *)malloc(arr_size * sizeof(double));
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int *temp_displacements = (int *)malloc(n_tasks * sizeof(int));
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if(temp_arr == NULL || temp_displacements == NULL) {
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printf("[-] Error: malloc failed!\n");
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exit(1);
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}
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for(int i = 0; i < n_tasks; i++)
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temp_displacements[i] = displacements[i];
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for(int i = 0; i < arr_size; i++) {
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int min_displacement_task_ix = 0;
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for(int j = 0; j < n_tasks; j++) {
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if(j != n_tasks -1 && temp_displacements[j] == displacements[j+1])
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continue;
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else if(j == n_tasks && temp_displacements[j] == arr_size -1)
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continue;
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if(arr[temp_displacements[min_displacement_task_ix]] > arr[temp_displacements[j]])
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min_displacement_task_ix = j;
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}
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temp_arr[i] = arr[temp_displacements[min_displacement_task_ix]];
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temp_displacements[min_displacement_task_ix]++;
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}
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return temp_arr;
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}
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void throw_err(int line, int err_code) {
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char err_buf[256];
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sprintf(err_buf, "[-] Error: %s -> %d", __FILE__, line);
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perror(err_buf);
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exit(err_code);
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}
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int main(int argc, char* argv[])
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{
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int taskid, ntasks;
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double *send_arr, *recv_arr;
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int *displacements, *counts;
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double start_time = MPI_Wtime();
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MPI_Init(&argc, &argv);
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signal(SIGSEGV, segfault_handler);
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MPI_Comm_rank(MPI_COMM_WORLD, &taskid);
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MPI_Comm_size(MPI_COMM_WORLD, &ntasks);
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if(DEBUG) {
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printf("[+] Task %d has started...\n", taskid);
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fflush(stdout);
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}
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if (taskid == 0) {
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//Setup array that we need to sort
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send_arr = setup_send_array(ARRAY_SIZE);
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}
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// Allocate memory for send_displacements and send_counts
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displacements = (int *)malloc(ntasks * sizeof(int));
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counts = (int *)malloc(ntasks * sizeof(int));
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if(displacements == NULL || counts == NULL) {
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printf("[-] Error: malloc failed!\n");
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exit(1);
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}
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// Setup displacements and counts
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setup_displacements_and_counts(displacements, counts, ntasks);
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if(DEBUG) {
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printf("[+] Setup displacements and counts done!\n");
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fflush(stdout);
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}
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// Setup recv array
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recv_arr = setup_recv_array(counts[taskid]);
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if(DEBUG) {
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printf("[+] Setup done!\n");
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fflush(stdout);
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}
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if(MPI_Barrier(MPI_COMM_WORLD) != MPI_SUCCESS)
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throw_err(__LINE__, errno);
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// Scatterv array to all processes
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if(MPI_Scatterv(send_arr, counts, displacements , MPI_DOUBLE, recv_arr, ARRAY_SIZE, MPI_DOUBLE, 0, MPI_COMM_WORLD) != MPI_SUCCESS)
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throw_err(__LINE__, errno);
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// Sort the array
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qsort(recv_arr, counts[taskid], sizeof(double), compare_doubles);
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if(DEBUG) {
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for(int i =0; i < counts[taskid]; i++) {
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printf("%f ", recv_arr[i]);
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}
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printf("---> tid: %d \n", taskid);
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fflush(stdout);
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}
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if(MPI_Barrier(MPI_COMM_WORLD) != MPI_SUCCESS)
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throw_err(__LINE__, errno);
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// Gather the array
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if(MPI_Gatherv(recv_arr, counts[taskid], MPI_DOUBLE, send_arr, counts, displacements, MPI_DOUBLE, 0, MPI_COMM_WORLD))
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throw_err(__LINE__, errno);
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if (taskid == 0) {
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send_arr = finalize_sort(send_arr, ARRAY_SIZE, displacements, ntasks);
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if(DEBUG) {
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for(int i = 0; i < ARRAY_SIZE; i++) {
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printf("%f ", send_arr[i]);
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}
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}
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double total_time = MPI_Wtime() - start_time;
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printf("\nTotal time: %f\n", total_time);
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}
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MPI_Finalize();
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return 0;
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// 500 000 000
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// 1: Total time: 28.816904
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// 2: Total time: 17.765614
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// 4: Total time: 13.663701
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// 8: Total time: 17.332404
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// 16: Total time: 19.667273
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// 32: Total time: 33.719451
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// 100 000 000
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// 1: Total time: 9.182889
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// 2: Total time: 4.406844
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// 4: Total time: 2.873339
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// 8: Total time: 3.302755
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// 16: Total time: 4.776216
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// 32: Total time: 7.725292
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// 1 000 000
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// 1: Total time: 1.516520
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// 2: Total time: 1.035112
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// 4: Total time: 1.114661
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// 8: Total time: 1.402073
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// 16: Total time: 2.096291
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// 32: Total time: 3.703796
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}
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