163 lines
4.2 KiB
Plaintext
163 lines
4.2 KiB
Plaintext
#include <vector>
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#include <fstream>
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#include <sstream>
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#include <iostream>
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#include <cuda_runtime.h>
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#include <algorithm>
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#include <chrono>
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__global__ void find_nearest_B(
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const float3 *__restrict__ A,
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const float3 *__restrict__ B,
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int *nearest_idx,
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int N, int M)
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{
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int idx = blockDim.x * blockIdx.x + threadIdx.x;
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if (idx >= N)
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return;
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float3 a = A[idx];
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float min_dist = 1e30f;
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int min_j = -1;
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for (int j = 0; j < M; ++j)
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{
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float dx = a.x - B[j].x;
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float dy = a.y - B[j].y;
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float dz = a.z - B[j].z;
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float dist = dx * dx + dy * dy + dz * dz;
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if (dist < min_dist)
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{
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min_dist = dist;
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min_j = j;
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}
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}
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nearest_idx[idx] = min_j;
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}
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std::vector<float3> load_coords_from_file(const std::string &filename)
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{
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std::vector<float3> coords;
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std::ifstream file(filename);
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if (!file)
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{
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std::cerr << "Unable to open file: " << filename << std::endl;
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return coords;
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}
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std::string line;
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while (std::getline(file, line))
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{
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std::istringstream iss(line);
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float x, y, z;
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if (iss >> x >> y >> z)
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{
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coords.push_back(make_float3(x, y, z));
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}
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}
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return coords;
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}
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void save_results_sorted(const std::string &filename,
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const std::vector<float3> &h_A,
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const std::vector<float3> &h_B,
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const std::vector<int> &indices)
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{
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struct Entry
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{
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float ax, az;
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float bx, bz;
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float dist;
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};
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std::vector<Entry> entries;
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for (size_t i = 0; i < indices.size(); ++i)
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{
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float3 a = h_A[i];
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float3 b = h_B[indices[i]];
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float dx = a.x - b.x;
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float dy = a.y - b.y;
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float dz = a.z - b.z;
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float dist = sqrtf(dx * dx + dy * dy + dz * dz);
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entries.push_back({a.x, a.z, b.x, b.z, dist});
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}
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std::sort(entries.begin(), entries.end(), [](const Entry &e1, const Entry &e2)
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{ return e1.dist < e2.dist; });
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std::ofstream file(filename);
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for (const auto &e : entries)
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{
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file << e.ax << " " << e.az << " "
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<< e.bx << " " << e.bz << " "
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<< e.dist << std::endl;
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}
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}
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int main()
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{
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auto t_start = std::chrono::high_resolution_clock::now();
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std::vector<float3> h_A = load_coords_from_file("data/cities.txt");
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std::vector<float3> h_B = load_coords_from_file("data/strongholds.txt");
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int N = h_A.size();
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int M = h_B.size();
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if (N == 0 || M == 0)
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{
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std::cerr << "Coords empty." << std::endl;
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return 1;
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}
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float3 *d_A;
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float3 *d_B;
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int *d_nearest_idx;
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cudaMalloc(&d_A, sizeof(float3) * N);
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cudaMalloc(&d_B, sizeof(float3) * M);
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cudaMalloc(&d_nearest_idx, sizeof(int) * N);
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cudaMemcpy(d_A, h_A.data(), sizeof(float3) * N, cudaMemcpyHostToDevice);
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cudaMemcpy(d_B, h_B.data(), sizeof(float3) * M, cudaMemcpyHostToDevice);
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int threads = 256;
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int blocks = (N + threads - 1) / threads;
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// ✅ CUDA 커널 시간 측정 시작
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cudaEvent_t start, stop;
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cudaEventCreate(&start);
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cudaEventCreate(&stop);
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cudaEventRecord(start);
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find_nearest_B<<<blocks, threads>>>(d_A, d_B, d_nearest_idx, N, M);
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cudaEventRecord(stop);
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cudaEventSynchronize(stop);
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float milliseconds = 0;
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cudaEventElapsedTime(&milliseconds, start, stop);
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std::cout << "CUDA kernel time: " << milliseconds << " ms" << std::endl;
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std::vector<int> h_nearest_idx(N);
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cudaMemcpy(h_nearest_idx.data(), d_nearest_idx, sizeof(int) * N, cudaMemcpyDeviceToHost);
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save_results_sorted("output.txt", h_A, h_B, h_nearest_idx);
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cudaFree(d_A);
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cudaFree(d_B);
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cudaFree(d_nearest_idx);
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auto t_end = std::chrono::high_resolution_clock::now();
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std::chrono::duration<double> elapsed = t_end - t_start;
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std::cout << "Total time: " << elapsed.count() * 1000.0 << " ms" << std::endl;
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std::cout << "Saved to output.txt." << std::endl;
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return 0;
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}
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