1 /* Copyright (c) 2017-2023. The SimGrid Team. All rights reserved. */
3 /* This program is free software; you can redistribute it and/or modify it
4 * under the terms of the license (GNU LGPL) which comes with this package. */
11 // Set the elements between buf[start] and buf[stop-1] to (i+value)%256
12 static void set(uint8_t *buf, size_t start, size_t stop, uint8_t value) {
13 for(size_t i = start; i < stop; i++) {
14 buf[i] = (uint8_t)((i + value) % 256);
18 // Return the number of times that an element is equal to (i+value)%256 between buf[start] and buf[stop-1].
19 static size_t count_all(const uint8_t* buf, size_t start, size_t stop, uint8_t value)
22 for(size_t i = start ; i < stop ; i++) {
23 if(buf[i] == (i+value)%256) {
30 // Return true iff the values from buf[start] to buf[stop-1] are all equal to (i+value)%256.
31 static int check_all(const uint8_t* buf, size_t start, size_t stop, uint8_t value)
33 size_t occ = count_all(buf, start, stop, value);
34 return occ == stop-start;
37 // Return true iff "enough" elements are equal to (i+value)%256 between buf[start] and buf[stop-1].
38 static int check_enough(const uint8_t* buf, size_t start, size_t stop, uint8_t value)
40 const unsigned int page_size = 0x1000;
41 size_t size = stop-start;
42 if(size <= 2*page_size) // we are not sure to have a whole page that is shared
44 size_t occ = count_all(buf, start, stop, value);
45 return occ >= size - 2*page_size;
48 int main(int argc, char *argv[])
50 MPI_Init(&argc, &argv);
53 size_t mem_size = 0x1000000;
54 size_t shared_blocks[] = {
62 int nb_blocks = (sizeof(shared_blocks)/sizeof(size_t))/2;
63 MPI_Comm_rank(MPI_COMM_WORLD, &rank);
64 MPI_Comm_size(MPI_COMM_WORLD, &size);
65 //Let's Allocate a shared memory buffer
67 buf = SMPI_PARTIAL_SHARED_MALLOC(mem_size, shared_blocks, nb_blocks);
68 set(buf, 0, mem_size, 0);
69 MPI_Barrier(MPI_COMM_WORLD);
71 // Process 0 write in shared blocks
73 for(int i = 0; i < nb_blocks; i++) {
74 size_t start = shared_blocks[2*i];
75 size_t stop = shared_blocks[2*i+1];
76 set(buf, start, stop, 42);
79 MPI_Barrier(MPI_COMM_WORLD);
80 // All processes check that their shared blocks have been written (at least partially)
81 for(int i = 0; i < nb_blocks; i++) {
82 size_t start = shared_blocks[2*i];
83 size_t stop = shared_blocks[2*i+1];
84 int is_shared = check_enough(buf, start, stop, 42);
85 printf("[%d] The result of the shared check for block (0x%zx, 0x%zx) is: %d\n", rank, start, stop, is_shared);
89 // Check the private blocks
90 MPI_Barrier(MPI_COMM_WORLD);
91 for(int i = 0; i < nb_blocks-1; i++) {
92 size_t start = shared_blocks[2*i+1];
93 size_t stop = shared_blocks[2*i+2];
94 int is_private = check_all(buf, start, stop, 0);
95 printf("[%d] The result of the private check for block (0x%zx, 0x%zx) is: %d\n", rank, start, stop, is_private);
98 SMPI_SHARED_FREE(buf);