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#include "kernel.cuh"
#include <stdio.h>
#include <cmath>
#include <iostream>
cudaError_t addWithCuda(int *c, const int *a, const int *b, unsigned int size);
__global__ void addKernel(int *c, const int *a, const int *b)
{
int i = threadIdx.x;
c[i] = a[i] + b[i];
}
const int blocksPerGrid = imin(32, (N + threadsPerBlock - 1) / threadsPerBlock);
bool float_equal(float a, float b) {
if (std::abs(a - b) < 1e1) return true;
return false;
}
int main()
{
float* a, * b, c = 0, * partial_c;
float* dev_a, * dev_b, * dev_partial_c;
a = new float[N];
b = new float[N];
partial_c = new float[blocksPerGrid];
cudaMalloc((void**)&dev_a, N * sizeof(float));
cudaMalloc((void**)&dev_b, N * sizeof(float));
cudaMalloc((void**)&dev_partial_c, blocksPerGrid * sizeof(float));
for (int i = 0; i < N; i++) {
a[i] = i;
b[i] = i * 2;
}
cudaMemcpy(dev_a, a, N * sizeof(float), cudaMemcpyHostToDevice);
cudaMemcpy(dev_b, b, N * sizeof(float), cudaMemcpyHostToDevice);
vector_add << <blocksPerGrid, threadsPerBlock >> > (dev_a, dev_b, dev_partial_c);
cudaMemcpy(partial_c, dev_partial_c, blocksPerGrid * sizeof(float), cudaMemcpyDeviceToHost);
for (int i = 0; i < blocksPerGrid; i++) {
c += partial_c[i];
}
double result = 0;
float* res_p = new float[blocksPerGrid];
for (int i = 0; i < N; i++) {
if (i == 368) {
printf("");
}
float temp = a[i] * b[i];
result = result + temp;
}
for (int i = 0; i < blocksPerGrid; i++) {
res_p[i] = 0;
for (int j = 0; j < threadsPerBlock; j++) {
res_p[i] += a[i * threadsPerBlock + j] * b[i * threadsPerBlock + j];
}
}
if (float_equal(result, c)) {
std::cout << "Test pass." << std::endl;
}
else {
std::cout << "Test error. CPU: " << result << ", GPU: " << c << std::endl;
}
cudaFree(dev_a);
cudaFree(dev_b);
cudaFree(dev_partial_c);
free(a);
free(b);
free(partial_c);
return 0;
}
#ifndef _KERNEL_CUH_
#define _KERNEL_CUH_
#include "cuda_runtime.h"
#include "device_launch_parameters.h"
#define imin(a,b) (a<b?a:b)
const int threadsPerBlock = 256;
const int N = 33 * 1024;
__global__ void vector_add(float* a, float* b, float* c);
#endif
#include <cstdio>
#include "kernel.cuh"
extern void __syncthreads();
__global__ void vector_add(float* a, float* b, float* c) {
__shared__ float res[threadsPerBlock];
int tid = threadIdx.x + blockIdx.x * blockDim.x;
int res_idx = threadIdx.x;
float temp = 0;
while (tid < N) {
temp += a[tid] * b[tid];
tid += blockDim.x * gridDim.x;
}
res[res_idx] = temp;
__syncthreads();
int i = blockDim.x / 2;
while (i != 0) {
if (res_idx < i) {
res[res_idx] += res[res_idx + i];
}
__syncthreads();
i = i / 2;
}
if (res_idx == 0) {
c[blockIdx.x] = res[0];
}
}
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