34 lines
1007 B
C++
34 lines
1007 B
C++
/*!
|
|
* Copyright (c) 2014 by Contributors
|
|
* \file basic.cc
|
|
* \brief This is an example demonstrating what is Allreduce
|
|
*
|
|
* \author Tianqi Chen
|
|
*/
|
|
#include <rabit.h>
|
|
using namespace rabit;
|
|
const int N = 3;
|
|
int main(int argc, char *argv[]) {
|
|
int a[N] = {0};
|
|
rabit::Init(argc, argv);
|
|
// lazy preparation function
|
|
auto prepare = [&]() {
|
|
printf("@node[%d] run prepare function\n", rabit::GetRank());
|
|
for (int i = 0; i < N; ++i) {
|
|
a[i] = rabit::GetRank() + i;
|
|
}
|
|
};
|
|
printf("@node[%d] before-allreduce: a={%d, %d, %d}\n",
|
|
rabit::GetRank(), a[0], a[1], a[2]);
|
|
// allreduce take max of each elements in all processes
|
|
Allreduce<op::Max>(&a[0], N, prepare);
|
|
printf("@node[%d] after-allreduce-sum: a={%d, %d, %d}\n",
|
|
rabit::GetRank(), a[0], a[1], a[2]);
|
|
// rum second allreduce
|
|
Allreduce<op::Sum>(&a[0], N);
|
|
printf("@node[%d] after-allreduce-max: a={%d, %d, %d}\n",
|
|
rabit::GetRank(), a[0], a[1], a[2]);
|
|
rabit::Finalize();
|
|
return 0;
|
|
}
|