424 lines
No EOL
13 KiB
C
424 lines
No EOL
13 KiB
C
#include <mpi.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#define ORDER_FORWARDS 1
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#define ORDER_BACKWARDS 2
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#define CTL_SIZE 3
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#define GENERIC_MAX(x, y) ((x) > (y) ? (x) : (y))
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#define GENERIC_MIN(x, y) ((x) < (y) ? (x) : (y))
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#define ENSURE_int(i) _Generic((i), int : (i))
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#define ENSURE_float(f) _Generic((f), float : (f))
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#define MAX(type, x, y) (type) GENERIC_MAX(ENSURE_##type(x), ENSURE_##type(y))
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#define MIN(type, x, y) (type) GENERIC_MIN(ENSURE_##type(x), ENSURE_##type(y))
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void local_quicksort(int *arr, int lo, int hi);
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char *string_of_list(int *arr, int len);
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void recursive_quicksort(int *integers, int n, int root, MPI_Comm comm);
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int main(int argc, char **argv) {
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int rank, p;
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MPI_Init(&argc, &argv);
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int n = atoi(argv[1]);
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MPI_Comm_rank(MPI_COMM_WORLD, &rank);
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MPI_Comm_size(MPI_COMM_WORLD, &p);
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// Generate integers
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int n_over_p = n / p;
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int integers[n_over_p];
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// Minor implementation detail: srand(0) is specially handled by glibc to
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// behave as if it was called with srand(1). To get around this, I'm seeding
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// with rank + 1
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//
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// See more: https://stackoverflow.com/a/27386563
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srand(rank + 1);
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for (int i = 0; i < n_over_p; ++i) {
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// TODO: For readability during debugging, I'm capping this
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integers[i] = rand() % 101;
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// printf(" - %d\n", integers[i]);
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}
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recursive_quicksort(integers, n, 0, MPI_COMM_WORLD);
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// sleep(1);
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// printf("[%d] after: %s\n", rank, string_of_list(integers, n_over_p));
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// The first node is responsible for collecting all the data and then
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// printing it out to the file MPI_Gather(const void *sendbuf, int
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// sendcount, MPI_INT, void *recvbuf,
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// int recvcount, MPI_INT, 0, MPI_COMM_WORLD);
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int recvbuf[n];
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MPI_Allgather(integers, n_over_p, MPI_INT, recvbuf, n_over_p, MPI_INT,
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MPI_COMM_WORLD);
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if (rank == 0) {
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FILE *f = fopen(argv[2], "w");
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// printf("integers: %s\n", string_of_list(recvbuf, n));
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for (int i = 0; i < p; i += 1) {
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printf("[%d] integers: %s\n", rank,
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string_of_list(&recvbuf[i * n_over_p], n_over_p));
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}
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fclose(f);
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}
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MPI_Finalize();
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printf("Done.\n");
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return 0;
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}
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// hi not inclusive
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void local_quicksort(int *arr, int lo, int hi) {
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int temp;
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if (lo >= hi || lo < 0)
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return;
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int pivot = arr[hi - 1];
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int pivot_idx = lo - 1;
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for (int j = lo; j < hi; ++j) {
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if (arr[j] < pivot) {
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pivot_idx += 1;
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temp = arr[j];
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arr[j] = arr[pivot_idx];
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arr[pivot_idx] = temp;
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}
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}
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pivot_idx += 1;
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temp = arr[hi - 1];
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arr[hi - 1] = arr[pivot_idx];
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arr[pivot_idx] = temp;
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// Recursive call
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local_quicksort(arr, lo, pivot_idx);
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local_quicksort(arr, pivot_idx + 1, hi);
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}
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char *string_of_list(int *arr, int len) {
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char *buffer = calloc(sizeof(char), 1000);
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int offset = 0; // Keep track of the current position in the buffer
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for (int i = 0; i < len; i++) {
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offset += sprintf(buffer + offset, "%d", arr[i]);
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if (i < len - 1) {
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// Add a separator (e.g., comma or space) if it's not the last element
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offset += sprintf(buffer + offset, " ");
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}
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}
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return buffer;
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}
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void recursive_quicksort(int *integers, int n, int root, MPI_Comm comm) {
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int rank, p;
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MPI_Comm_size(comm, &p);
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MPI_Comm_rank(comm, &rank);
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if (p == 1) {
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// Recursion base case: just sort it serially
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local_quicksort(integers, 0, n);
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printf("Quicksorted: %s\n", string_of_list(integers, n));
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return;
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}
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sleep(1);
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printf("\n\n");
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int n_over_p_max = (n + p - 1) / p;
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int n_over_p = n / p;
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if (rank == root)
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n_over_p += n - p * n_over_p;
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printf(
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"[%d] :::::::::::::::::::::::::::: RECURSIVE QUICKSORT (n=%d, n/p=%d)\n",
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rank, n, n_over_p);
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// Locally sort
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// printf("[%d] Numbers before: %s\n", rank,
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// string_of_list(integers, n_over_p));
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local_quicksort(integers, 0, n_over_p);
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printf("[%d] Numbers after first sort: %s\n", rank,
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string_of_list(integers, n_over_p));
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// Select a pivot.
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// This pivot is broadcasted to all nodes
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int pivot;
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{
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// First, select a random element
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int rand_el = integers[rand() % n_over_p];
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// Gather it
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int rand_els[p];
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MPI_Gather(&rand_el, 1, MPI_INT, rand_els, 1, MPI_INT, root, comm);
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// Get the median
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if (rank == root) {
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// Sort
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local_quicksort(rand_els, 0, p);
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// Get the middle element
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pivot = rand_els[p / 2];
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}
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MPI_Bcast(&pivot, 1, MPI_INT, root, comm);
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}
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printf("[%d] Broadcasted pivot: %d\n", rank, pivot);
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// Determine where the boundary between S (lower) and L (higher) lies
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int boundary;
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for (int i = 0; i < n_over_p; ++i) {
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if (integers[i] >= pivot) {
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boundary = i;
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break;
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}
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}
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int S_lo = 0, S_hi = boundary;
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int L_lo = boundary, L_hi = n_over_p;
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int S_size = S_hi - S_lo, L_size = L_hi - L_lo;
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printf("[%d] S: [%d - %d] (%d), L: [%d - %d] (%d)\n", rank, S_lo, S_hi,
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S_size, L_lo, L_hi, L_size);
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// Perform global arrangement
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int S_global_end, L_reverse_end, S_global_max_end;
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MPI_Scan(&S_size, &S_global_end, 1, MPI_INT, MPI_SUM, comm);
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MPI_Scan(&L_size, &L_reverse_end, 1, MPI_INT, MPI_SUM, comm);
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// printf("[%d] bruh %d\n", rank, S_global_end);
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// Get the boundary element between S and L
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MPI_Allreduce(&S_global_end, &S_global_max_end, 1, MPI_INT, MPI_MAX, comm);
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int S_global_start = S_global_end - S_size,
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L_reverse_start = L_reverse_end - L_size,
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L_global_start = n - L_reverse_end, L_global_end = n - L_reverse_start;
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printf("[%d] Prefixed S: [%d - %d], Prefixed L: [%d - %d]\n", rank,
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S_global_start, S_global_end - 1, L_global_start, L_global_end - 1);
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int S_starting_process = S_global_start / n_over_p,
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L_starting_process = L_global_start / n_over_p;
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int S_offset = S_global_start % n_over_p,
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L_offset = L_global_start % n_over_p;
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int *integers_recv_buf = calloc(sizeof(int), n);
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int S_ctl[p * CTL_SIZE];
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int L_ctl[p * CTL_SIZE];
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int recvpart[n_over_p];
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int send_ctl[p * CTL_SIZE];
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int ctl_send_counts[p];
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int ctl_send_displs[p];
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int send_counts[p];
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int send_displs[p];
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int recv_counts[p];
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int recv_displs[p];
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for (int i = 0; i < p; ++i) {
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send_counts[i] = n_over_p;
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send_displs[i] = i * n_over_p;
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S_ctl[i * CTL_SIZE] = 0;
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S_ctl[i * CTL_SIZE + 1] = -1;
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S_ctl[i * CTL_SIZE + 2] = -1;
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L_ctl[i * CTL_SIZE] = 0;
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L_ctl[i * CTL_SIZE + 1] = -1;
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L_ctl[i * CTL_SIZE + 2] = -1;
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ctl_send_counts[i] = CTL_SIZE;
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ctl_send_displs[i] = i * CTL_SIZE;
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recv_counts[i] = CTL_SIZE;
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recv_displs[i] = i * CTL_SIZE;
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}
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// Send S to the correct target
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{
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for (int i = 0; i < p; ++i) {
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send_ctl[i * CTL_SIZE] = 0;
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send_ctl[i * CTL_SIZE + 1] = -1;
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send_ctl[i * CTL_SIZE + 2] = -1;
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}
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for (int i = S_lo, dest_pos = S_global_start,
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processor = S_starting_process;
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i < S_hi;) {
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int next_break = MIN(int, S_global_end,
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MIN(int, dest_pos + (S_hi - S_lo),
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(dest_pos / n_over_p) * n_over_p + n_over_p));
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int count = next_break - dest_pos;
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int from_local_start = i, from_local_end = i + count;
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int from_global_start = rank * n_over_p + from_local_start,
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from_global_end = from_global_start + count;
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int to_global_start = dest_pos, to_global_end = dest_pos + count;
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int to_local_start = to_global_start - processor * n_over_p,
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to_local_end = to_global_end - processor * n_over_p;
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printf("[%d] S ->> (count=%d), from local [%d..%d] {%d..%d} -to-> "
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"p#%d [%d..%d] {%d..%d}\n",
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rank, count, from_local_start, from_local_end, from_global_start,
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from_global_end, processor, to_local_start, to_local_end,
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to_global_start, to_global_end);
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send_ctl[processor * CTL_SIZE] = count;
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send_ctl[processor * CTL_SIZE + 1] = from_global_start;
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send_ctl[processor * CTL_SIZE + 2] = to_local_start;
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i += count;
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dest_pos += count;
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processor += 1;
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}
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MPI_Alltoallv(send_ctl, ctl_send_counts, ctl_send_displs, MPI_INT, S_ctl,
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recv_counts, recv_displs, MPI_INT, comm);
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}
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// Send L to the correct target
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{
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for (int i = 0; i < p; ++i) {
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send_ctl[i * CTL_SIZE] = 0;
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send_ctl[i * CTL_SIZE + 1] = -1;
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send_ctl[i * CTL_SIZE + 2] = -1;
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}
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for (int i = L_lo, dest_pos = L_global_start,
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processor = L_starting_process;
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i < L_hi;) {
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int next_break = MIN(int, L_global_end,
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MIN(int, dest_pos + (L_hi - L_lo),
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(dest_pos / n_over_p) * n_over_p + n_over_p));
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int count = next_break - dest_pos;
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int from_local_start = i, from_local_end = i + count;
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int from_global_start = rank * n_over_p + from_local_start,
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from_global_end = from_global_start + count;
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int to_global_start = dest_pos, to_global_end = dest_pos + count;
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int to_local_start = to_global_start - processor * n_over_p,
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to_local_end = to_global_end - processor * n_over_p;
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printf("[%d] L ->> (count=%d), from local [%d..%d] {%d..%d} -to-> "
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"p#%d [%d..%d] {%d..%d}\n",
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rank, count, from_local_start, from_local_end, from_global_start,
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from_global_end, processor, to_local_start, to_local_end,
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to_global_start, to_global_end);
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send_ctl[processor * CTL_SIZE] = count;
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send_ctl[processor * CTL_SIZE + 1] = from_global_start;
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send_ctl[processor * CTL_SIZE + 2] = to_local_start;
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i += count;
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dest_pos += count;
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processor += 1;
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}
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MPI_Alltoallv(send_ctl, ctl_send_counts, ctl_send_displs, MPI_INT, L_ctl,
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recv_counts, recv_displs, MPI_INT, comm);
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}
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// After sending S and L information
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for (int i = 0; i < p; ++i) {
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recv_counts[i] = n_over_p;
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recv_displs[i] = i * n_over_p;
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}
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// MPI_Alltoallv(integers, send_counts, send_displs, MPI_INT,
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// integers_recv_buf,
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// recv_counts, recv_displs, MPI_INT, MPI_COMM_WORLD);
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MPI_Allgather(integers, n_over_p, MPI_INT, integers_recv_buf, n_over_p,
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MPI_INT, comm);
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// printf("[%d] ints: %s\n", rank, string_of_list(integers_recv_buf, n));
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for (int i = 0; i < p; ++i) {
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}
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for (int i = 0; i < p; ++i) {
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int count = S_ctl[i * CTL_SIZE];
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int from_global_start = S_ctl[i * CTL_SIZE + 1];
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int to_local_start = S_ctl[i * CTL_SIZE + 2];
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if (count > 0) {
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printf(
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"[%d] <<- S received (%d) from processor %d {%d..%d} to [% d..% d]\n",
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rank, count, i, from_global_start, from_global_start + count,
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to_local_start, to_local_start + count);
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for (int j = 0; j < count; ++j) {
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integers[to_local_start + j] = integers_recv_buf[from_global_start + j];
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}
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}
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}
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for (int i = 0; i < p; ++i) {
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int count = L_ctl[i * CTL_SIZE];
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int from_global_start = L_ctl[i * CTL_SIZE + 1];
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int to_local_start = L_ctl[i * CTL_SIZE + 2];
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if (count > 0) {
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printf(
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"[%d] <<- S received (%d) from processor %d {%d..%d} to [% d..% d]\n",
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rank, count, i, from_global_start, from_global_start + count,
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to_local_start, to_local_start + count);
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for (int j = 0; j < count; ++j) {
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integers[to_local_start + j] = integers_recv_buf[from_global_start + j];
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}
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}
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}
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printf("[%d] after: %s\n", rank, string_of_list(integers, n_over_p));
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// Now, determine which processes should be responsible for taking the S and L
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// arrays
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// Specifically, the part where it's split, break the tie to see if it goes
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// down or up
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int colors[p];
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int p_of_split = S_global_max_end / n_over_p;
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int split_point = S_global_max_end % n_over_p;
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// printf("[%d] p_of_split = %d / %d = %d\n", rank, S_global_max_end,
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// n_over_p,
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// p_of_split);
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int S_split_add = split_point, L_split_sub = n_over_p - split_point;
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int lo_start = 0, lo_end;
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int hi_start, hi_end = p;
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if (split_point > n_over_p / 2) {
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// Belongs to the lower group
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lo_end = hi_start = p_of_split + 1;
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} else {
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// Belongs to the higher group
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lo_end = hi_start = p_of_split;
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}
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int child_root = -1;
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for (int i = 0; i < p; ++i) {
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if (i < lo_end)
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colors[i] = 100;
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else {
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colors[i] = 200;
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if (child_root == -1)
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child_root = i;
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}
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}
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// MPI_Comm child;
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// MPI_Comm_split(comm, colors[rank], rank, &child);
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// printf("[%d] Recursing...\n", rank);
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// int child_size;
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// MPI_Comm_size(child, &child_size);
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// int start_at = 0, new_n = child_size * n_over_p;
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// if (colors[rank] == 100) {
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// new_n += S_split_add;
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// } else {
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// new_n -= L_split_sub;
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// if (rank == p_of_split)
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// start_at = split_point;
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// }
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// recursive_quicksort(integers, n, child_root, child);
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// printf("[%d] Done recursing.\n", rank);
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// MPI_Comm_free(&child);
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} |