--- /dev/null
+/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil ; -*- */
+/*
+ * (C) 2003 by Argonne National Laboratory.
+ * See COPYRIGHT in top-level directory.
+ */
+
+/* MPI-3 distributed linked list construction example
+ * --------------------------------------------------
+ *
+ * Construct a distributed shared linked list using proposed MPI-3 dynamic
+ * windows. Initially process 0 creates the head of the list, attaches it to
+ * the window, and broadcasts the pointer to all processes. Each process p then
+ * appends N new elements to the list when the tail reaches process p-1.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <mpi.h>
+#include <assert.h>
+#include "mpitest.h"
+
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
+#define NUM_ELEMS 1000
+#define MAX_NPROBE nproc
+#define MIN_NPROBE 1
+#define ELEM_PER_ROW 16
+
+#define MIN(X,Y) ((X < Y) ? (X) : (Y))
+#define MAX(X,Y) ((X > Y) ? (X) : (Y))
+
+/* Linked list pointer */
+typedef struct {
+ int rank;
+ MPI_Aint disp;
+} llist_ptr_t;
+
+/* Linked list element */
+typedef struct {
+ int value;
+ llist_ptr_t next;
+} llist_elem_t;
+
+static const llist_ptr_t nil = { -1, (MPI_Aint) MPI_BOTTOM };
+static const int verbose = 0;
+static const int print_perf = 0;
+
+/* List of locally allocated list elements. */
+static llist_elem_t **my_elems = NULL;
+static int my_elems_size = 0;
+static int my_elems_count = 0;
+
+/* Allocate a new shared linked list element */
+MPI_Aint alloc_elem(int value, MPI_Win win) {
+ MPI_Aint disp;
+ llist_elem_t *elem_ptr;
+
+ /* Allocate the new element and register it with the window */
+ MPI_Alloc_mem(sizeof(llist_elem_t), MPI_INFO_NULL, &elem_ptr);
+ elem_ptr->value = value;
+ elem_ptr->next = nil;
+ MPI_Win_attach(win, elem_ptr, sizeof(llist_elem_t));
+
+ /* Add the element to the list of local elements so we can free it later. */
+ if (my_elems_size == my_elems_count) {
+ my_elems_size += 100;
+ my_elems = realloc(my_elems, my_elems_size*sizeof(void*));
+ }
+ my_elems[my_elems_count] = elem_ptr;
+ my_elems_count++;
+
+ MPI_Get_address(elem_ptr, &disp);
+ return disp;
+}
+
+int main(int argc, char **argv) {
+ int procid, nproc, i, j, my_nelem;
+ int pollint = 0;
+ double time;
+ MPI_Win llist_win;
+ llist_ptr_t head_ptr, tail_ptr;
+
+ MPI_Init(&argc, &argv);
+
+ MPI_Comm_rank(MPI_COMM_WORLD, &procid);
+ MPI_Comm_size(MPI_COMM_WORLD, &nproc);
+
+ MPI_Win_create_dynamic(MPI_INFO_NULL, MPI_COMM_WORLD, &llist_win);
+
+ /* Process 0 creates the head node */
+ if (procid == 0)
+ head_ptr.disp = alloc_elem(procid, llist_win);
+
+ /* Broadcast the head pointer to everyone */
+ head_ptr.rank = 0;
+ MPI_Bcast(&head_ptr.disp, 1, MPI_AINT, 0, MPI_COMM_WORLD);
+ tail_ptr = head_ptr;
+
+ /* All processes append NUM_ELEMS elements to the list; rank 0 has already
+ * appended an element. */
+ if (procid == 0)
+ i = 1;
+ else
+ i = 0;
+ my_nelem = NUM_ELEMS/nproc;
+ if (procid < NUM_ELEMS % nproc)
+ my_nelem++;
+
+ MPI_Barrier(MPI_COMM_WORLD);
+ time = MPI_Wtime();
+
+ for ( ; i < my_nelem; i++) {
+ llist_ptr_t new_elem_ptr;
+ int success = 0;
+
+ /* Create a new list element and register it with the window */
+ new_elem_ptr.rank = procid;
+ new_elem_ptr.disp = alloc_elem(procid, llist_win);
+
+ /* Append the new node to the list. This might take multiple attempts if
+ others have already appended and our tail pointer is stale. */
+ do {
+ int flag;
+
+ /* The tail is at my left neighbor, append my element. */
+ if (tail_ptr.rank == (procid + nproc-1) % nproc)
+ {
+ if (verbose)
+ printf("%d: Appending to <%d, %p>\n", procid, tail_ptr.rank, (void*) tail_ptr.disp);
+
+ MPI_Win_lock(MPI_LOCK_EXCLUSIVE, tail_ptr.rank, 0, llist_win);
+#if USE_ACC
+ MPI_Accumulate(&new_elem_ptr, sizeof(llist_ptr_t), MPI_BYTE, tail_ptr.rank,
+ (MPI_Aint) &(((llist_elem_t*)tail_ptr.disp)->next), sizeof(llist_ptr_t),
+ MPI_BYTE, MPI_REPLACE, llist_win);
+#else
+ MPI_Put(&new_elem_ptr, sizeof(llist_ptr_t), MPI_BYTE, tail_ptr.rank,
+ (MPI_Aint) &(((llist_elem_t*)tail_ptr.disp)->next), sizeof(llist_ptr_t),
+ MPI_BYTE, llist_win);
+#endif
+ MPI_Win_unlock(tail_ptr.rank, llist_win);
+
+ success = 1;
+ tail_ptr = new_elem_ptr;
+ }
+
+ /* Otherwise, chase the tail. */
+ else
+ {
+ llist_ptr_t next_tail_ptr;
+
+ MPI_Win_lock(MPI_LOCK_EXCLUSIVE, tail_ptr.rank, 0, llist_win);
+#if USE_ACC
+ MPI_Get_accumulate( NULL, 0, MPI_DATATYPE_NULL, &next_tail_ptr,
+ sizeof(llist_ptr_t), MPI_BYTE, tail_ptr.rank,
+ (MPI_Aint) &(((llist_elem_t*)tail_ptr.disp)->next),
+ sizeof(llist_ptr_t), MPI_BYTE, MPI_NO_OP, llist_win);
+#else
+ MPI_Get(&next_tail_ptr, sizeof(llist_ptr_t), MPI_BYTE, tail_ptr.rank,
+ (MPI_Aint) &(((llist_elem_t*)tail_ptr.disp)->next),
+ sizeof(llist_ptr_t), MPI_BYTE, llist_win);
+#endif
+ MPI_Win_unlock(tail_ptr.rank, llist_win);
+
+ if (next_tail_ptr.rank != nil.rank) {
+ if (verbose)
+ printf("%d: Chasing to <%d, %p>\n", procid, next_tail_ptr.rank, (void*) next_tail_ptr.disp);
+ tail_ptr = next_tail_ptr;
+ pollint = MAX(MIN_NPROBE, pollint/2);
+ }
+ else {
+ for (j = 0; j < pollint; j++)
+ MPI_Iprobe(MPI_ANY_SOURCE, MPI_ANY_TAG, MPI_COMM_WORLD, &flag, MPI_STATUS_IGNORE);
+
+ pollint = MIN(MAX_NPROBE, pollint*2);
+ }
+ }
+ } while (!success);
+ }
+
+ MPI_Barrier(MPI_COMM_WORLD);
+ time = MPI_Wtime() - time;
+
+ /* Traverse the list and verify that all processes inserted exactly the correct
+ number of elements. */
+ if (procid == 0) {
+ int errors = 0;
+ int *counts, count = 0;
+
+ counts = (int*) malloc(sizeof(int) * nproc);
+ assert(counts != NULL);
+
+ for (i = 0; i < nproc; i++)
+ counts[i] = 0;
+
+ tail_ptr = head_ptr;
+
+ MPI_Win_lock_all(0, llist_win);
+
+ /* Walk the list and tally up the number of elements inserted by each rank */
+ while (tail_ptr.disp != nil.disp) {
+ llist_elem_t elem;
+
+ MPI_Get(&elem, sizeof(llist_elem_t), MPI_BYTE,
+ tail_ptr.rank, tail_ptr.disp, sizeof(llist_elem_t), MPI_BYTE, llist_win);
+
+ MPI_Win_flush(tail_ptr.rank, llist_win);
+
+ tail_ptr = elem.next;
+
+ assert(elem.value >= 0 && elem.value < nproc);
+ counts[elem.value]++;
+ count++;
+
+ if (verbose) {
+ int last_elem = tail_ptr.disp == nil.disp;
+ printf("%2d%s", elem.value, last_elem ? "" : " -> ");
+ if (count % ELEM_PER_ROW == 0 && !last_elem)
+ printf("\n");
+ }
+ }
+
+ MPI_Win_unlock_all(llist_win);
+
+ if (verbose)
+ printf("\n\n");
+
+ /* Verify the counts we collected */
+ for (i = 0; i < nproc; i++) {
+ int expected;
+
+ expected = NUM_ELEMS/nproc;
+ if (i < NUM_ELEMS % nproc)
+ expected++;
+
+ if (counts[i] != expected) {
+ printf("Error: Rank %d inserted %d elements, expected %d\n", i, counts[i], expected);
+ errors++;
+ }
+ }
+
+ printf("%s\n", errors == 0 ? " No Errors" : "FAIL");
+ free(counts);
+ }
+
+ if (print_perf) {
+ double max_time;
+
+ MPI_Reduce(&time, &max_time, 1, MPI_DOUBLE, MPI_MAX, 0, MPI_COMM_WORLD);
+
+ if (procid == 0) {
+ printf("Total time = %0.2f sec, elem/sec = %0.2f, sec/elem = %0.2f usec\n", max_time, NUM_ELEMS/max_time, max_time/NUM_ELEMS*1.0e6);
+ }
+ }
+
+ MPI_Win_free(&llist_win);
+
+ /* Free all the elements in the list */
+ for ( ; my_elems_count > 0; my_elems_count--)
+ MPI_Free_mem(my_elems[my_elems_count-1]);
+
+ MPI_Finalize();
+ return 0;
+}
