init

cpp_omp/main.cpp

@@ -0,0 +1,81 @@
+#include <algorithm>
+#include <chrono>
+#include <cmath>
+#include <cstdint>
+#include <iostream>
+#include <random>
+#include <string>
+#include <vector>
+#ifdef _OPENMP
+#include <omp.h>
+#endif
+
+static void init_vec(std::vector<float> &v, uint64_t seed) {
+  std::mt19937 rng(static_cast<uint32_t>(seed));
+  std::uniform_real_distribution<float> dist(-1.0f, 1.0f);
+  for (auto &x : v) x = dist(rng);
+}
+
+int main(int argc, char **argv) {
+  size_t N = 100000000;
+  int iters = 10;
+  if (argc >= 2) N = static_cast<size_t>(std::stoull(argv[1]));
+  if (argc >= 3) iters = std::stoi(argv[2]);
+
+  std::vector<float> A(N), B(N), C(N), D(N), E(N);
+  init_vec(A, 1);
+  init_vec(B, 2);
+  init_vec(C, 3);
+
+  volatile float sink = 0.0f;
+#pragma omp parallel for reduction(+:sink) if(N>10000)
+  for (int i = 0; i < std::min<size_t>(N, 1000); ++i) {
+    float d = A[i] + B[i];
+    float e = d * C[i] + B[i];
+    sink += e;
+  }
+
+  auto start = std::chrono::high_resolution_clock::now();
+
+  double sum_result = 0.0;
+  for (int it = 0; it < iters; ++it) {
+#pragma omp parallel for if(N>10000)
+    for (long long i = 0; i < static_cast<long long>(N); ++i) {
+      D[i] = A[i] + B[i];
+    }
+#pragma omp parallel for if(N>10000)
+    for (long long i = 0; i < static_cast<long long>(N); ++i) {
+      E[i] = D[i] * C[i] + B[i];
+    }
+    double local_sum = 0.0;
+#pragma omp parallel
+    {
+      double thread_sum = 0.0;
+#pragma omp for nowait
+      for (long long i = 0; i < static_cast<long long>(N); ++i) {
+        thread_sum += static_cast<double>(E[i]);
+      }
+#pragma omp atomic
+      sum_result += thread_sum;
+    }
+  }
+
+  auto end = std::chrono::high_resolution_clock::now();
+  double ms = std::chrono::duration<double, std::milli>(end - start).count();
+
+  double bytes_per_iter = 7.0 * N * sizeof(float);
+  double gbps = (bytes_per_iter * iters) / (ms / 1000.0) / 1e9;
+
+  int threads = 1;
+#ifdef _OPENMP
+  threads = omp_get_max_threads();
+#endif
+
+  std::cout << "CPP OpenMP\n";
+  std::cout << "threads=" << threads << "\n";
+  std::cout << "N=" << N << " iters=" << iters << "\n";
+  std::cout << "time_ms=" << ms << "\n";
+  std::cout << "throughput_GBps=" << gbps << "\n";
+  std::cout << "result=" << sum_result << "\n";
+  return (sink == 12345.678f) ? 0 : 0;
+}