CUDA编程--实现并行矩阵乘法【80行代码】

- 日理万妓 2022-04-03 15:19 209阅读 0赞

## 简述 ##

这里只写了方阵之间的乘法，但是本质上都是一样的。

*  我测试过100规模的方阵之间的乘法，没有问题。

## 代码 ##

*  读取文件**data.txt**
 *  数据格式就是一个数值N，然后来连续的两个N\*N的矩阵。用空格隔开。

#include "cuda_runtime.h"
    #include "device_launch_parameters.h"
    #include <iostream>
    #include <fstream>
    #include <stdio.h>
    // Kernal:
    __global__ void MatrixMultiply(int *a, int * b, int *c, int N) { 
    	int tx = threadIdx.x + blockIdx.x * blockDim.x;
    	int ty = threadIdx.y + blockIdx.y * blockDim.y;
    	if (tx < N && ty < N) { 
    		int sum = 0;
    		for (int k = 0; k < N; ++k) { 
    			int adata = a[tx * N + k];
    			int bdata = b[k * N + ty];
    			sum += adata * bdata;
    		}
    		c[tx * N + ty] = sum;
    	}
    }
    
    cudaError_t matrixMultiplyWithCuda(int *a, int *b, int *c, size_t size);
    
    int main()
    { 
    	std::ifstream in("data.txt");
    	int N;
    	in >> N;
    	if (in.fail()) { 
    		printf("Something wrong\n");
    	}
    	else { 
    		printf("Success read\n");
    	}
    	// host initial
    	int *a = new int[N * N];
    	int *b = new int[N * N];
    	int *c = new int[N * N];
    
    	// read 
    	for (int i = 0; i < N; ++i)
    		for (int j = 0; j < N; ++j) in >> a[i * N + j];
    
    	for (int i = 0; i < N; ++i)
    		for (int j = 0; j < N; ++j) in >> b[i * N + j];
    
    	cudaError_t cudaStatus = matrixMultiplyWithCuda(a, b, c, N);
    
    	for (int i = 0; i < N; ++i) { 
    		for (int j = 0; j < N; ++j) std::cout << c[i * N + j]<<" ";
    		std::cout << std::endl;
    	}
    	cudaStatus = cudaThreadExit();
    
    	// host free 
    	delete[] a;
    	delete[] b;
    	delete[] c;
    	return 0;
    }
    cudaError_t matrixMultiplyWithCuda(int *a, int *b, int *c, size_t N) { 
    	int *dev_a = 0;
    	int *dev_b = 0;
    	int *dev_c = 0;
    	cudaError_t cudaStatus;
    	cudaStatus = cudaMalloc((void**)&dev_a, N * N * sizeof(int));
    	cudaStatus = cudaMalloc((void**)&dev_b, N * N * sizeof(int));
    	cudaStatus = cudaMalloc((void**)&dev_c, N * N * sizeof(int));
    	cudaStatus = cudaMemcpy(dev_a, a, N * N * sizeof(int), cudaMemcpyHostToDevice);
    	cudaStatus = cudaMemcpy(dev_b, b, N * N * sizeof(int), cudaMemcpyHostToDevice);
    	if (cudaStatus != cudaSuccess) { 
    		printf("Something wrong\n");
    		goto Error;
    	}
    	// kernal invocation 
    	dim3 threadPerBlock(32, 32);
    	dim3 numBlocks(N / threadPerBlock.x + 1, N / threadPerBlock.y + 1);
    	MatrixMultiply<<<numBlocks, threadPerBlock>>>(dev_a, dev_b, dev_c, N);
    	if (cudaStatus != cudaSuccess) { 
    		printf( "Calculate wrong\n");
    		goto Error;
    	}
    	cudaStatus = cudaMemcpy(c, dev_c, N * N * sizeof(int), cudaMemcpyDeviceToHost);
    Error:
    	cudaFree(dev_a);
    	cudaFree(dev_b);
    	cudaFree(dev_c);
    	return cudaStatus;
    }

### 写入文件的 版本 ###

（也改成了浮点数运算了）

#include "cuda_runtime.h"
    #include "device_launch_parameters.h"
    #include <iostream>
    #include <fstream>
    #include <stdio.h>
    // Kernal:
    __global__ void MatrixMultiply(float *a, float * b, float *c, int N) { 
    	int tx = threadIdx.x + blockIdx.x * blockDim.x;
    	int ty = threadIdx.y + blockIdx.y * blockDim.y;
    	if (tx < N && ty < N) { 
    		float sum = 0;
    		for (int k = 0; k < N; ++k) { 
    			float adata = a[tx * N + k];
    			float bdata = b[k * N + ty];
    			sum += adata * bdata;
    		}
    		c[tx * N + ty] = sum;
    	}
    }
    
    cudaError_t matrixMultiplyWithCuda(float *a, float *b, float *c, size_t size);
    
    int main()
    { 
    	std::ifstream in("data.txt");
    	int N;
    	in >> N;
    	if (in.fail()) { 
    		printf("Something wrong\n");
    	}
    	else { 
    		printf("Success read\n");
    	}
    	// host initial
    	float *a = new float[N * N];
    	float *b = new float[N * N];
    	float *c = new float[N * N];
    
    	// read 
    	for (int i = 0; i < N; ++i)
    		for (int j = 0; j < N; ++j) in >> a[i * N + j];
    
    	for (int i = 0; i < N; ++i)
    		for (int j = 0; j < N; ++j) in >> b[i * N + j];
    
    	cudaError_t cudaStatus = matrixMultiplyWithCuda(a, b, c, N);
    
    	std::ofstream out("output.txt");
    	for (int i = 0; i < N; ++i) { 
    		for (int j = 0; j < N; ++j) out << c[i * N + j]<<" ";
    		out << std::endl;
    	}
    	cudaStatus = cudaThreadExit();
    
    	// host free 
    	delete[] a;
    	delete[] b;
    	delete[] c;
    	return 0;
    }
    cudaError_t matrixMultiplyWithCuda(float *a, float *b, float *c, size_t N) { 
    	float *dev_a = 0;
    	float *dev_b = 0;
    	float *dev_c = 0;
    	cudaError_t cudaStatus;
    	cudaStatus = cudaMalloc((void**)&dev_a, N * N * sizeof(int));
    	cudaStatus = cudaMalloc((void**)&dev_b, N * N * sizeof(int));
    	cudaStatus = cudaMalloc((void**)&dev_c, N * N * sizeof(int));
    	cudaStatus = cudaMemcpy(dev_a, a, N * N * sizeof(int), cudaMemcpyHostToDevice);
    	cudaStatus = cudaMemcpy(dev_b, b, N * N * sizeof(int), cudaMemcpyHostToDevice);
    	if (cudaStatus != cudaSuccess) { 
    		printf("Something wrong\n");
    		goto Error;
    	}
    	// kernal invocation 
    	dim3 threadPerBlock(32, 32);
    	dim3 numBlocks(N / threadPerBlock.x + 1, N / threadPerBlock.y + 1);
    	MatrixMultiply<<<numBlocks, threadPerBlock>>>(dev_a, dev_b, dev_c, N);
    	if (cudaStatus != cudaSuccess) { 
    		printf( "Calculate wrong\n");
    		goto Error;
    	}
    	cudaStatus = cudaMemcpy(c, dev_c, N * N * sizeof(int), cudaMemcpyDeviceToHost);
    Error:
    	cudaFree(dev_a);
    	cudaFree(dev_b);
    	cudaFree(dev_c);
    	return cudaStatus;
    }