188 lines
4.7 KiB
C
188 lines
4.7 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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#include <string.h>
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// 100MB is equal to 100 * 1024 * 1024 bytes, so you will need to allocate (100 * 1024 * 1024) / 4 = 25,000,000 integers. <-- chatGPT ftw
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#define ARRAY_SIZE 25000000
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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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int* setup_send_array(int size) {
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int *arr = (int *)malloc(size * sizeof(int));
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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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if (i % 2 == 0 ){
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arr[i] = 1;
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} else {
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arr[i] = 0;
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}
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}
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// Set random bit to two
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arr[rand() % size] = 2;
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return arr;
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}
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int* setup_recv_array(int n_elements) {
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int *recv_arr = (int *)malloc(n_elements * sizeof(int));
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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;
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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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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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int *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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MPI_Request request;
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MPI_Status status;
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int flag = 0;
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char *message = "Hello World!\0";
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int message_len = strlen(message) + 1;
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char recv_message[message_len];
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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_INT, recv_arr, ARRAY_SIZE, MPI_INT, 0, MPI_COMM_WORLD) != MPI_SUCCESS)
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throw_err(__LINE__, errno);
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if(MPI_Irecv(recv_message, message_len, MPI_CHAR, 0, 0, MPI_COMM_WORLD, &request))
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throw_err(__LINE__, errno);
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for(int i =0; i < counts[taskid]; i++) {
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if(DEBUG)
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printf("%d ", recv_arr[i]);
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if(i % 20 == 0) {
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if(MPI_Test(&request, &flag, &status))
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throw_err(__LINE__, errno);
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if(flag) {
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printf("[+] Recieved stop signal!\n");
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break;
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}
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}
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if(recv_arr[i] == 2) {
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printf("[+] Found 2 at index %d! --> taskid: %d\n", displacements[taskid] + i, taskid);
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if(MPI_Isend(message, message_len, MPI_CHAR, 0, 0, MPI_COMM_WORLD, &request))
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throw_err(__LINE__, errno);
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break;
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}
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}
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// Gather the array
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if(MPI_Gatherv(recv_arr, counts[taskid], MPI_INT, send_arr, counts, displacements, MPI_INT, 0, MPI_COMM_WORLD))
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throw_err(__LINE__, errno);
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if (taskid == 0) {
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if(DEBUG) {
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for(int i = 0; i < ARRAY_SIZE; i++) {
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printf("%d ", 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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// 1: 0.616473
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// 2: 0.742917
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// 4: 0.804409
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// 8: 0.782405
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// 16: 6.045285
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// 32: 3.036735
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}
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