Я новичок в CUDA, и я пытался понять, что я делаю здесь не так. CUDA занимает больше времени, чем просто использование процессора для умножения матрицы. Если я делаю что-то не так, пожалуйста, дайте мне знать.
Вот мой код:
#include "cuda_runtime.h"
#include "device_launch_parameters.h"
#include <stdio.h>
#include <stdlib.h>
#include <cstdlib>
#include <assert.h>
#include <time.h>
#define size 100 // Matrix size
#define cols size // Matrix width
#define rows size // Matrix height
void checkCUDAError(const char *msg)
{
cudaError_t err = cudaGetLastError();
if( cudaSuccess != err)
{
fprintf(stderr, "Cuda error: %s: %s.\n", msg, cudaGetErrorString( err) );
exit(EXIT_FAILURE);
}
}
__global__ void matrixMul( int *A, int *B, int *C)
{
int bx = blockIdx.x; // Block index
int tx = threadIdx.x; // Thread index
int ts = blockDim.x; // number of threads
// Declaration of the shared memory C element
extern __shared__ int c_element_sum[];
c_element_sum[tx] = A[tx+((bx/ts)*ts)] * B[(bx%ts)+(tx*ts)];
//Block until all threads in the block have written their data to shared mem
__syncthreads();
int sum;
for(int i=0; i<ts; i++){
if(i==0){
sum=c_element_sum[i];
}
else{
sum+=c_element_sum[i];
}
}
C[bx] = sum;
}
/////////////////////////////////////////////////////////
// Program main
/////////////////////////////////////////////////////////
int main(int argc, char** argv)
{
//create timer.
clock_t t1, t2;
//start timer
t1=clock();
//allocate host memory for matrices
unsigned int size_A = cols * rows;
unsigned int mem_size_A = sizeof(int) * size_A;
int* mA = (int*) malloc(mem_size_A);
unsigned int size_B = cols * rows;
unsigned int mem_size_B = sizeof(int) * size_B;
int* mB = (int*) malloc(mem_size_B);
unsigned int size_C = cols * rows;
unsigned int mem_size_C = sizeof(int) * size_C;
int* mC = (int*) malloc(mem_size_C);
//initialize host memory
for (int i = 0; i < size_A; ++i){
mA[i] = 1;
mB[i] = 1;
mC[i] = 0;
}
// allocate device memory
int* d_mA;
int* d_mB;
int* d_mC;
cudaMalloc((void**) &d_mA, mem_size_A);
cudaMalloc((void**) &d_mB, mem_size_B);
cudaMalloc((void**) &d_mC, mem_size_C);
//copy host memory to device (A and B)
cudaMemcpy(d_mA, mA, mem_size_A, cudaMemcpyHostToDevice);
cudaMemcpy(d_mB, mB, mem_size_B, cudaMemcpyHostToDevice);
cudaMemcpy(d_mC, mC, mem_size_C, cudaMemcpyHostToDevice);
// setup execution parameters
int numThreadsPerBlock = cols;
int numBlocks = (cols * rows);
int sharedMemSize = numThreadsPerBlock * sizeof(int);
dim3 dimGrid(numBlocks);
dim3 dimBlock(numThreadsPerBlock);
// execute the kernel
matrixMul <<< dimGrid, dimBlock, sharedMemSize >>>(d_mA, d_mB, d_mC);
//Block until device has completed
cudaThreadSynchronize();
// check if kernel execution generated an error
// Check for any CUDA errors
checkCUDAError("kernel invocation");
//copy result from device to host
cudaMemcpy(mC, d_mC, mem_size_C, cudaMemcpyDeviceToHost);
// Check for any CUDA errors
checkCUDAError("memcpy");
//stop timer
t2 = clock();
//check results
for (int i = 0; i < size_C; ++i){
assert(mC[i] == cols);
}
//clean up memory
free(mA);
free(mB);
free(mC);
cudaFree(d_mA);
cudaFree(d_mB);
cudaFree(d_mC);
printf("WITH CUDA - clocks: %d \n\n", t2-t1);
//////////////////////////////
///////// CPU ONLY //////////
/////////////////////////////
//create timer.
clock_t cpu_t1, cpu_t2;
//start timer
cpu_t1=clock();
//allocate host memory for matrices
unsigned int cpu_size_A = cols * rows;
unsigned int cpu_mem_size_A = sizeof(int) * cpu_size_A;
int* cpu_mA = (int*) malloc(cpu_mem_size_A);
unsigned int cpu_size_B = cols * rows;
unsigned int cpu_mem_size_B = sizeof(int) * cpu_size_B;
int* cpu_mB = (int*) malloc(cpu_mem_size_B);
unsigned int cpu_size_C = cols * rows;
unsigned int cpu_mem_size_C = sizeof(int) * cpu_size_C;
int* cpu_mC = (int*) malloc(cpu_mem_size_C);
//initialize host memory
for (int i = 0; i < cpu_size_A; ++i){
cpu_mA[i] = 1;
cpu_mB[i] = 1;
cpu_mC[i] = 0;
}
int ts = cols;
for(int bx=0; bx<(cols*rows);bx++){
int sum = 0;
for(int tx=0; tx<cols; tx++){
sum += cpu_mA[tx+((bx/ts)*ts)] * cpu_mB[(bx%ts)+(tx*ts)];
}
cpu_mC[bx]=sum;
}
//stop timer
cpu_t2 = clock();
//check results
for (int i = 0; i < cpu_size_C; ++i){
assert(cpu_mC[i] == cols);
}
//clean up memory
free(cpu_mA);
free(cpu_mB);
free(cpu_mC);
printf("CPU ONLY - clocks: %d \n\n", cpu_t2-cpu_t1);
return 0;
}