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/* Copyright (c) 2017-2018. The SimGrid Team. All rights reserved. */
/* This program is free software; you can redistribute it and/or modify it
* under the terms of the license (GNU LGPL) which comes with this package. */
#include <stdio.h>
#include <mpi.h>
#include <stdint.h>
#include <inttypes.h>
#include <assert.h>
// Set the elements between buf[start] and buf[stop-1] to (i+value)%256
static void set(uint8_t *buf, size_t start, size_t stop, uint8_t value) {
for(size_t i = start; i < stop; i++) {
buf[i] = (i+value)%256;
}
}
// Return the number of times that an element is equal to (i+value)%256 between buf[start] and buf[stop-1].
static int count_all(uint8_t *buf, size_t start, size_t stop, uint8_t value) {
size_t occ = 0;
for(size_t i = start ; i < stop ; i++) {
if(buf[i] == (i+value)%256) {
occ ++;
}
}
return occ;
}
// Return true iff the values from buf[start] to buf[stop-1] are all equal to (i+value)%256.
static int check_all(uint8_t *buf, size_t start, size_t stop, uint8_t value) {
size_t occ = count_all(buf, start, stop, value);
return occ == stop-start;
}
// Return true iff "enough" elements are equal to (i+value)%256 between buf[start] and buf[stop-1].
static int check_enough(uint8_t *buf, size_t start, size_t stop, uint8_t value) {
int page_size = 0x1000;
size_t size = stop-start;
if(size <= 2*page_size) // we are not sure to have a whole page that is shared
return 1;
size_t occ = count_all(buf, start, stop, value);
return occ >= size - 2*page_size;
}
int main(int argc, char *argv[])
{
MPI_Init(&argc, &argv);
int rank;
int size;
size_t mem_size = 0x1000000;
size_t shared_blocks[] = {
0, 0x123456,
0x130000, 0x130001,
0x345678, 0x345789,
0x444444, 0x555555,
0x555556, 0x560000,
0x800000, 0x1000000
};
int nb_blocks = (sizeof(shared_blocks)/sizeof(size_t))/2;
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
MPI_Comm_size(MPI_COMM_WORLD, &size);
//Let's Allocate a shared memory buffer
assert(size%2 == 0);
uint8_t *buf;
buf = SMPI_PARTIAL_SHARED_MALLOC(mem_size, shared_blocks, nb_blocks);
memset(buf, rank, mem_size);
MPI_Barrier(MPI_COMM_WORLD);
// Even processes write their rank in private blocks
if(rank%2 == 0) {
for(int i = 0; i < nb_blocks-1; i++) {
size_t start = shared_blocks[2*i+1];
size_t stop = shared_blocks[2*i+2];
set(buf, start, stop, rank);
}
}
// Then, even processes send their buffer to their successor
if(rank%2 == 0) {
MPI_Send(buf, mem_size, MPI_UINT8_T, rank+1, 0, MPI_COMM_WORLD);
}
else {
MPI_Recv(buf, mem_size, MPI_UINT8_T, rank-1, 0, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
}
// Odd processes verify that they successfully received the message
if(rank%2 == 1) {
for(int i = 0; i < nb_blocks-1; i++) {
size_t start = shared_blocks[2*i+1];
size_t stop = shared_blocks[2*i+2];
int comm = check_all(buf, start, stop, rank-1);
printf("[%d] The result of the (normal) communication check for block (0x%zx, 0x%zx) is: %d\n", rank, start, stop, comm);
}
memset(buf, rank, mem_size);
}
MPI_Barrier(MPI_COMM_WORLD);
// Then, even processes send a sub-part of their buffer their successor
// Note that the last block should not be copied entirely
if(rank%2 == 0) {
MPI_Send(buf+0x10000, mem_size-0xa00000, MPI_UINT8_T, rank+1, 0, MPI_COMM_WORLD);
}
else {
MPI_Recv(buf+0x10000, mem_size-0xa00000, MPI_UINT8_T, rank-1, 0, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
}
// Odd processes verify that they successfully received the message
if(rank%2 == 1) {
for(int i = 0; i < nb_blocks-1; i++) {
size_t start = shared_blocks[2*i+1];
size_t stop = shared_blocks[2*i+2];
int comm = check_all(buf, start, stop, rank-1);
printf("[%d] The result of the (shifted) communication check for block (0x%zx, 0x%zx) is: %d\n", rank, start, stop, comm);
}
}
SMPI_SHARED_FREE(buf);
MPI_Finalize();
return 0;
}
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