File: capacity_mix_threads.cpp

package info (click to toggle)
llvm-toolchain-16 1%3A16.0.6-15~deb12u1
  • links: PTS, VCS
  • area: main
  • in suites: bookworm
  • size: 1,634,792 kB
  • sloc: cpp: 6,179,261; ansic: 1,216,205; asm: 741,319; python: 196,614; objc: 75,325; f90: 49,640; lisp: 32,396; pascal: 12,286; sh: 9,394; perl: 7,442; ml: 5,494; awk: 3,523; makefile: 2,723; javascript: 1,206; xml: 886; fortran: 581; cs: 573
file content (45 lines) | stat: -rw-r--r-- 1,049 bytes parent folder | download | duplicates (12) 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
 
// RUN: %libomp-cxx-compile-and-run

#include <omp.h>

#include <algorithm>
#include <cassert>
#include <chrono>
#include <thread>
#include <vector>

void dummy_root() {
  // omp_get_max_threads() will do middle initialization
  int nthreads = omp_get_max_threads();
  std::this_thread::sleep_for(std::chrono::milliseconds(1000));
}

int main(int argc, char *argv[]) {
  const int N = std::min(std::max(std::max(32, 4 * omp_get_max_threads()),
                                  4 * omp_get_num_procs()),
                         std::numeric_limits<int>::max());

  std::vector<int> data(N);

  // Create a new thread to initialize the OpenMP RTL. The new thread will not
  // be taken as the "initial thread".
  std::thread root(dummy_root);

#pragma omp parallel for num_threads(N)
  for (unsigned i = 0; i < N; ++i) {
    data[i] = i;
  }

#pragma omp parallel for num_threads(N + 1)
  for (unsigned i = 0; i < N; ++i) {
    data[i] += i;
  }

  for (unsigned i = 0; i < N; ++i) {
    assert(data[i] == 2 * i);
  }

  root.join();

  return 0;
}